diff --git a/accessible/jsat/AccessFu.jsm b/accessible/jsat/AccessFu.jsm
index c6b16b38fbc1..f78b870c8368 100644
--- a/accessible/jsat/AccessFu.jsm
+++ b/accessible/jsat/AccessFu.jsm
@@ -342,9 +342,9 @@ this.AccessFu = { // jshint ignore:line
       case 'remote-browser-shown':
       case 'inprocess-browser-shown':
       {
-        // Ignore notifications that aren't from a BrowserOrApp
+        // Ignore notifications that aren't from a Browser
         let frameLoader = aSubject.QueryInterface(Ci.nsIFrameLoader);
-        if (!frameLoader.ownerIsMozBrowserOrAppFrame) {
+        if (!frameLoader.ownerIsMozBrowserFrame) {
           return;
         }
         this._handleMessageManager(frameLoader.messageManager);
diff --git a/b2g/chrome/content/devtools/hud.js b/b2g/chrome/content/devtools/hud.js
index 64e9d553d883..08e7906b31aa 100644
--- a/b2g/chrome/content/devtools/hud.js
+++ b/b2g/chrome/content/devtools/hud.js
@@ -36,8 +36,6 @@ XPCOMUtils.defineLazyGetter(this, 'MemoryFront', function() {
   return devtools.require('devtools/server/actors/memory').MemoryFront;
 });
 
-Cu.import('resource://gre/modules/Frames.jsm');
-
 var _telemetryDebug = false;
 
 function telemetryDebug(...args) {
@@ -54,7 +52,6 @@ function telemetryDebug(...args) {
  */
 var developerHUD = {
 
-  _targets: new Map(),
   _histograms: new Set(),
   _customHistograms: new Set(),
   _client: null,
@@ -99,13 +96,6 @@ var developerHUD = {
       }
     }
 
-    Frames.addObserver(this);
-
-    let appFrames = Frames.list().filter(frame => frame.getAttribute('mozapp'));
-    for (let frame of appFrames) {
-      this.trackFrame(frame);
-    }
-
     SettingsListener.observe('hud.logging', this._logging, enabled => {
       this._logging = enabled;
     });
@@ -124,63 +114,10 @@ var developerHUD = {
       return;
     }
 
-    for (let frame of this._targets.keys()) {
-      this.untrackFrame(frame);
-    }
-
-    Frames.removeObserver(this);
-
     this._client.close();
     delete this._client;
   },
 
-  /**
-   * This method will ask all registered watchers to track and update metrics
-   * on an app frame.
-   */
-  trackFrame(frame) {
-    if (this._targets.has(frame)) {
-      return;
-    }
-
-    DebuggerServer.connectToChild(this._conn, frame).then(actor => {
-      let target = new Target(frame, actor);
-      this._targets.set(frame, target);
-
-      for (let w of this._watchers) {
-        w.trackTarget(target);
-      }
-    });
-  },
-
-  untrackFrame(frame) {
-    let target = this._targets.get(frame);
-    if (target) {
-      for (let w of this._watchers) {
-        w.untrackTarget(target);
-      }
-
-      target.destroy();
-      this._targets.delete(frame);
-    }
-  },
-
-  onFrameCreated(frame, isFirstAppFrame) {
-    let mozapp = frame.getAttribute('mozapp');
-    if (!mozapp) {
-      return;
-    }
-    this.trackFrame(frame);
-  },
-
-  onFrameDestroyed(frame, isLastAppFrame) {
-    let mozapp = frame.getAttribute('mozapp');
-    if (!mozapp) {
-      return;
-    }
-    this.untrackFrame(frame);
-  },
-
   log(message) {
     if (this._logging) {
       dump(DEVELOPER_HUD_LOG_PREFIX + ': ' + message + '\n');
diff --git a/b2g/chrome/content/shell.js b/b2g/chrome/content/shell.js
index d483f9a64f53..68979056955a 100644
--- a/b2g/chrome/content/shell.js
+++ b/b2g/chrome/content/shell.js
@@ -358,7 +358,6 @@ var shell = {
       document.createElementNS('http://www.w3.org/1999/xhtml', 'html:iframe');
     systemAppFrame.setAttribute('id', 'systemapp');
     systemAppFrame.setAttribute('mozbrowser', 'true');
-    systemAppFrame.setAttribute('mozapp', manifestURL);
     systemAppFrame.setAttribute('allowfullscreen', 'true');
     systemAppFrame.setAttribute('src', 'blank.html');
     let container = document.getElementById('container');
diff --git a/b2g/chrome/content/shell_remote.js b/b2g/chrome/content/shell_remote.js
index 1f1115ef0a02..7c273a96f959 100644
--- a/b2g/chrome/content/shell_remote.js
+++ b/b2g/chrome/content/shell_remote.js
@@ -53,7 +53,6 @@ var remoteShell = {
       document.createElementNS("http://www.w3.org/1999/xhtml", "html:iframe");
     systemAppFrame.setAttribute("id", this.id);
     systemAppFrame.setAttribute("mozbrowser", "true");
-    systemAppFrame.setAttribute("mozapp", manifestURL);
     systemAppFrame.setAttribute("allowfullscreen", "true");
     systemAppFrame.setAttribute("src", "blank.html");
 
diff --git a/b2g/components/DebuggerActors.js b/b2g/components/DebuggerActors.js
index 318c46e68844..da77a794be04 100644
--- a/b2g/components/DebuggerActors.js
+++ b/b2g/components/DebuggerActors.js
@@ -30,10 +30,7 @@ function B2GTabList(connection) {
 B2GTabList.prototype = Object.create(BrowserTabList.prototype);
 
 B2GTabList.prototype._getBrowsers = function() {
-  return Frames.list().filter(frame => {
-    // Ignore app frames
-    return !frame.getAttribute("mozapp");
-  });
+  return Frames.list();
 };
 
 B2GTabList.prototype._getSelectedBrowser = function() {
@@ -59,21 +56,11 @@ B2GTabList.prototype._listenForEventsIf = function(shouldListen) {
 };
 
 B2GTabList.prototype.onFrameCreated = function(frame) {
-  let mozapp = frame.getAttribute("mozapp");
-  if (mozapp) {
-    // Ignore app frames
-    return;
-  }
   this._notifyListChanged();
   this._checkListening();
 };
 
 B2GTabList.prototype.onFrameDestroyed = function(frame) {
-  let mozapp = frame.getAttribute("mozapp");
-  if (mozapp) {
-    // Ignore app frames
-    return;
-  }
   let actor = this._actorByBrowser.get(frame);
   if (actor) {
     this._handleActorClose(actor, frame);
diff --git a/b2g/components/ErrorPage.jsm b/b2g/components/ErrorPage.jsm
index 2c0c64c21262..f320c3e7f84d 100644
--- a/b2g/components/ErrorPage.jsm
+++ b/b2g/components/ErrorPage.jsm
@@ -176,8 +176,8 @@ var ErrorPage = {
 
   observe: function errorPageObserve(aSubject, aTopic, aData) {
     let frameLoader = aSubject.QueryInterface(Ci.nsIFrameLoader);
-    // Ignore notifications that aren't from a BrowserOrApp
-    if (!frameLoader.ownerIsMozBrowserOrAppFrame) {
+    // Ignore notifications that aren't from a Browser
+    if (!frameLoader.ownerIsMozBrowserFrame) {
       return;
     }
     this._listenError(frameLoader);
diff --git a/b2g/components/Frames.jsm b/b2g/components/Frames.jsm
index 0eb00cb4cb7b..dae3618e8b91 100644
--- a/b2g/components/Frames.jsm
+++ b/b2g/components/Frames.jsm
@@ -19,9 +19,6 @@ const Observer = {
   // the FrameDestroyed event with a frame reference.
   _frames: new Map(),
 
-  // Also save current number of iframes opened by app
-  _apps: new Map(),
-
   start: function () {
     Services.obs.addObserver(this, 'remote-browser-shown', false);
     Services.obs.addObserver(this, 'inprocess-browser-shown', false);
@@ -30,10 +27,6 @@ const Observer = {
     SystemAppProxy.getFrames().forEach(frame => {
       let mm = frame.QueryInterface(Ci.nsIFrameLoaderOwner).frameLoader.messageManager;
       this._frames.set(mm, frame);
-      let mozapp = frame.getAttribute('mozapp');
-      if (mozapp) {
-        this._apps.set(mozapp, (this._apps.get(mozapp) || 0) + 1);
-      }
     });
   },
 
@@ -42,7 +35,6 @@ const Observer = {
     Services.obs.removeObserver(this, 'inprocess-browser-shown');
     Services.obs.removeObserver(this, 'message-manager-close');
     this._frames.clear();
-    this._apps.clear();
   },
 
   observe: function (subject, topic, data) {
@@ -70,17 +62,9 @@ const Observer = {
   onMessageManagerCreated: function (mm, frame) {
     this._frames.set(mm, frame);
 
-    let isFirstAppFrame = null;
-    let mozapp = frame.getAttribute('mozapp');
-    if (mozapp) {
-      let count = (this._apps.get(mozapp) || 0) + 1;
-      this._apps.set(mozapp, count);
-      isFirstAppFrame = (count === 1);
-    }
-
     listeners.forEach(function (listener) {
       try {
-        listener.onFrameCreated(frame, isFirstAppFrame);
+        listener.onFrameCreated(frame);
       } catch(e) {
         dump('Exception while calling Frames.jsm listener:' + e + '\n' +
              e.stack + '\n');
@@ -97,17 +81,9 @@ const Observer = {
 
     this._frames.delete(mm);
 
-    let isLastAppFrame = null;
-    let mozapp = frame.getAttribute('mozapp');
-    if (mozapp) {
-      let count = (this._apps.get(mozapp) || 0) - 1;
-      this._apps.set(mozapp, count);
-      isLastAppFrame = (count === 0);
-    }
-
     listeners.forEach(function (listener) {
       try {
-        listener.onFrameDestroyed(frame, isLastAppFrame);
+        listener.onFrameDestroyed(frame);
       } catch(e) {
         dump('Exception while calling Frames.jsm listener:' + e + '\n' +
              e.stack + '\n');
diff --git a/b2g/components/SafeMode.jsm b/b2g/components/SafeMode.jsm
index 9f9342f679e5..375052e7c400 100644
--- a/b2g/components/SafeMode.jsm
+++ b/b2g/components/SafeMode.jsm
@@ -76,7 +76,6 @@ this.SafeMode = {
     debug("Registry is ready, loading " + url);
     let frame = document.createElementNS("http://www.w3.org/1999/xhtml", "html:iframe");
     frame.setAttribute("mozbrowser", "true");
-    frame.setAttribute("mozapp", shell.manifestURL);
     frame.setAttribute("id", "systemapp"); // To keep screen.js happy.
     let contentBrowser = document.body.appendChild(frame);
 
diff --git a/b2g/simulator/custom-prefs.js b/b2g/simulator/custom-prefs.js
index 634a9cebea8e..2ff59a167025 100644
--- a/b2g/simulator/custom-prefs.js
+++ b/b2g/simulator/custom-prefs.js
@@ -1,6 +1,5 @@
 user_pref("devtools.debugger.prompt-connection", false);
 user_pref("devtools.debugger.forbid-certified-apps", false);
-user_pref("devtools.apps.forbidden-permissions", "");
 user_pref("b2g.software-buttons", true);
 
 // Required for Mulet in order to run the debugger server from the command line
diff --git a/caps/nsIPrincipal.idl b/caps/nsIPrincipal.idl
index c9c461d3b829..b9d407affe58 100644
--- a/caps/nsIPrincipal.idl
+++ b/caps/nsIPrincipal.idl
@@ -298,10 +298,10 @@ interface nsIPrincipal : nsISerializable
 
     /**
      * Returns true iff the principal is inside an isolated mozbrowser element.
-     * <iframe mozbrowser mozapp> and <xul:browser> are not considered to be
-     * mozbrowser elements.  <iframe mozbrowser noisolation> does not count as
-     * isolated since isolation is disabled.  Isolation can only be disabled if
-     * the containing document is chrome.
+     * <xul:browser> is not considered to be a mozbrowser element.
+     * <iframe mozbrowser noisolation> does not count as isolated since
+     * isolation is disabled.  Isolation can only be disabled if the
+     * containing document is chrome.
      */
     [infallible] readonly attribute boolean isInIsolatedMozBrowserElement;
 
diff --git a/caps/tests/mochitest/mochitest.ini b/caps/tests/mochitest/mochitest.ini
index 866553ea265f..666a735ae78e 100644
--- a/caps/tests/mochitest/mochitest.ini
+++ b/caps/tests/mochitest/mochitest.ini
@@ -4,7 +4,6 @@ support-files =
   file_disableScript.html
   !/js/xpconnect/tests/mochitest/file_empty.html
 
-[test_app_principal_equality.html]
 [test_bug246699.html]
 [test_bug292789.html]
 [test_bug423375.html]
diff --git a/caps/tests/mochitest/test_app_principal_equality.html b/caps/tests/mochitest/test_app_principal_equality.html
deleted file mode 100644
index f59f1f7893fe..000000000000
--- a/caps/tests/mochitest/test_app_principal_equality.html
+++ /dev/null
@@ -1,88 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=777467
--->
-<head>
-  <meta charset="utf-8">
-  <title>Test app principal's equality</title>
-  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
-</head>
-<body>
-<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=777467">Mozilla Bug 777467</a>
-<p id="display"></p>
-<script>
-
-/** Test for app principal's equality **/
-
-SimpleTest.waitForExplicitFinish();
-
-var permissions = new Promise(resolve => {
-  SpecialPowers.pushPermissions(
-    [{ type: "browser", allow: true, context: document },
-     { type: "embed-apps", allow: true, context: document }],
-    resolve);
-});
-
-permissions.then(() => {
-  $('content').innerHTML =
-    '<iframe src="error404"></iframe>\n' +
-    '<iframe mozbrowser src="error404"></iframe>\n' +
-    '<iframe mozapp="http://example.org/manifest.webapp" mozbrowser src="error404"></iframe>';
-
-  var iframes = document.getElementsByTagName("iframe");
-  var promises = []
-  for (var i = 0; i < promises.length; ++i) {
-    promises.push(new Promise(resolve => {
-      iframes[i].addEventListener("load", resolve);
-    }));
-  }
-
-  return Promise.all(promises);
-});
-
-var prefs = new Promise(resolve => {
-  SpecialPowers.pushPrefEnv(
-    { set: [[ "dom.mozBrowserFramesEnabled", true ],
-            [ "dom.ipc.browser_frames.oop_by_default", false ]] },
-    resolve);
-});
-</script>
-<div id="content" style="display: none;">
-</div>
-<pre id="test">
-<script type="application/javascript">
-
-function canAccessDocument(win) {
-  var result = true;
-  try {
-    win.document;
-  } catch(e) {
-    result = false;
-  }
-  return result;
-}
-
-var loaded = new Promise(resolve => addLoadEvent(resolve));
-
-Promise.all([ permissions, prefs, loaded ]).then(runTest);
-
-function runTest() {
-  // Test the witness frame (we can access same-origin frame).
-  is(canAccessDocument(frames[0]), true,
-     "should be able to access the first frame");
-
-  // Test different app/browserElement frames.
-  for (var i=1; i<frames.length; ++i) {
-    is(canAccessDocument(frames[i]), false,
-       "should not be able to access the other frames");
-  }
-
-  SimpleTest.finish();
-}
-
-</script>
-</pre>
-</body>
-</html>
diff --git a/devtools/server/actors/webconsole.js b/devtools/server/actors/webconsole.js
index 95926f6e649f..6a6ad67e6d71 100644
--- a/devtools/server/actors/webconsole.js
+++ b/devtools/server/actors/webconsole.js
@@ -569,11 +569,9 @@ WebConsoleActor.prototype =
 
     let startedListeners = [];
     let window = !this.parentActor.isRootActor ? this.window : null;
-    let appId = null;
     let messageManager = null;
 
     if (this._parentIsContentActor) {
-      appId = this.parentActor.docShell.appId;
       messageManager = this.parentActor.messageManager;
     }
 
@@ -604,16 +602,16 @@ WebConsoleActor.prototype =
             // Create a StackTraceCollector that's going to be shared both by the
             // NetworkMonitorChild (getting messages about requests from parent) and
             // by the NetworkMonitor that directly watches service workers requests.
-            this.stackTraceCollector = new StackTraceCollector({ window, appId });
+            this.stackTraceCollector = new StackTraceCollector({ window });
             this.stackTraceCollector.init();
 
             let processBoundary = Services.appinfo.processType !=
                                   Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT;
-            if ((appId || messageManager) && processBoundary) {
+            if (messageManager && processBoundary) {
               // Start a network monitor in the parent process to listen to
               // most requests than happen in parent
               this.networkMonitor =
-                new NetworkMonitorChild(appId, this.parentActor.outerWindowID,
+                new NetworkMonitorChild(this.parentActor.outerWindowID,
                                         messageManager, this.conn, this);
               this.networkMonitor.init();
               // Spawn also one in the child to listen to service workers
diff --git a/devtools/shared/layout/utils.js b/devtools/shared/layout/utils.js
index 1e6ab5075ada..54f3ba84e519 100644
--- a/devtools/shared/layout/utils.js
+++ b/devtools/shared/layout/utils.js
@@ -37,12 +37,12 @@ function getTopWindow(win) {
                     .getInterface(Ci.nsIWebNavigation)
                     .QueryInterface(Ci.nsIDocShell);
 
-  if (!docShell.isMozBrowserOrApp) {
+  if (!docShell.isMozBrowser) {
     return win.top;
   }
 
   let topDocShell =
-    docShell.getSameTypeRootTreeItemIgnoreBrowserAndAppBoundaries();
+    docShell.getSameTypeRootTreeItemIgnoreBrowserBoundaries();
 
   return topDocShell
           ? topDocShell.contentViewer.DOMDocument.defaultView
@@ -98,12 +98,12 @@ function getParentWindow(win) {
                  .getInterface(Ci.nsIWebNavigation)
                  .QueryInterface(Ci.nsIDocShell);
 
-  if (!docShell.isMozBrowserOrApp) {
+  if (!docShell.isMozBrowser) {
     return win.parent;
   }
 
   let parentDocShell =
-    docShell.getSameTypeParentIgnoreBrowserAndAppBoundaries();
+    docShell.getSameTypeParentIgnoreBrowserBoundaries();
 
   return parentDocShell
           ? parentDocShell.contentViewer.DOMDocument.defaultView
diff --git a/devtools/shared/webconsole/network-monitor.js b/devtools/shared/webconsole/network-monitor.js
index dec0be39d385..a90dc525f377 100644
--- a/devtools/shared/webconsole/network-monitor.js
+++ b/devtools/shared/webconsole/network-monitor.js
@@ -1508,8 +1508,6 @@ NetworkMonitor.prototype = {
  * data to the WebConsoleActor or to a NetworkEventActor.
  *
  * @constructor
- * @param number appId
- *        The web appId of the child process.
  * @param number outerWindowID
  *        The outerWindowID of the TabActor's main window.
  * @param nsIMessageManager messageManager
@@ -1519,8 +1517,7 @@ NetworkMonitor.prototype = {
  * @param object owner
  *        The WebConsoleActor that is listening for the network requests.
  */
-function NetworkMonitorChild(appId, outerWindowID, messageManager, conn, owner) {
-  this.appId = appId;
+function NetworkMonitorChild(outerWindowID, messageManager, conn, owner) {
   this.outerWindowID = outerWindowID;
   this.conn = conn;
   this.owner = owner;
@@ -1533,7 +1530,6 @@ function NetworkMonitorChild(appId, outerWindowID, messageManager, conn, owner)
 exports.NetworkMonitorChild = NetworkMonitorChild;
 
 NetworkMonitorChild.prototype = {
-  appId: null,
   owner: null,
   _netEvents: null,
   _saveRequestAndResponseBodies: true,
@@ -1581,7 +1577,6 @@ NetworkMonitorChild.prototype = {
     mm.addMessageListener("debug:netmonitor:updateEvent",
                           this._onUpdateEvent);
     mm.sendAsyncMessage("debug:netmonitor", {
-      appId: this.appId,
       outerWindowID: this.outerWindowID,
       action: "start",
     });
diff --git a/docshell/base/LoadContext.cpp b/docshell/base/LoadContext.cpp
index c4095a951a61..723d15a51e87 100644
--- a/docshell/base/LoadContext.cpp
+++ b/docshell/base/LoadContext.cpp
@@ -169,17 +169,6 @@ LoadContext::GetIsInIsolatedMozBrowserElement(bool* aIsInIsolatedMozBrowserEleme
   return NS_OK;
 }
 
-NS_IMETHODIMP
-LoadContext::GetAppId(uint32_t* aAppId)
-{
-  MOZ_ASSERT(mIsNotNull);
-
-  NS_ENSURE_ARG_POINTER(aAppId);
-
-  *aAppId = mOriginAttributes.mAppId;
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 LoadContext::GetOriginAttributes(JS::MutableHandleValue aAttrs)
 {
diff --git a/docshell/base/nsDSURIContentListener.cpp b/docshell/base/nsDSURIContentListener.cpp
index cfac54f7f4ec..65e5220325c8 100644
--- a/docshell/base/nsDSURIContentListener.cpp
+++ b/docshell/base/nsDSURIContentListener.cpp
@@ -331,7 +331,7 @@ nsDSURIContentListener::CheckOneFrameOptionsPolicy(nsIHttpChannel* aHttpChannel,
            curDocShellItem->GetParent(getter_AddRefs(parentDocShellItem))) &&
          parentDocShellItem) {
     nsCOMPtr<nsIDocShell> curDocShell = do_QueryInterface(curDocShellItem);
-    if (curDocShell && curDocShell->GetIsMozBrowserOrApp()) {
+    if (curDocShell && curDocShell->GetIsMozBrowser()) {
       break;
     }
 
diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index 6411a8a93f35..1bab8c0c7639 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -2603,7 +2603,7 @@ nsDocShell::GetFullscreenAllowed(bool* aFullscreenAllowed)
 NS_IMETHODIMP
 nsDocShell::SetFullscreenAllowed(bool aFullscreenAllowed)
 {
-  if (!nsIDocShell::GetIsMozBrowserOrApp()) {
+  if (!nsIDocShell::GetIsMozBrowser()) {
     // Only allow setting of fullscreenAllowed on content/process boundaries.
     // At non-boundaries the fullscreenAllowed attribute is calculated based on
     // whether all enclosing frames have the "mozFullscreenAllowed" attribute
@@ -3433,7 +3433,7 @@ nsDocShell::GetSameTypeParent(nsIDocShellTreeItem** aParent)
   NS_ENSURE_ARG_POINTER(aParent);
   *aParent = nullptr;
 
-  if (nsIDocShell::GetIsMozBrowserOrApp()) {
+  if (nsIDocShell::GetIsMozBrowser()) {
     return NS_OK;
   }
 
@@ -3450,7 +3450,7 @@ nsDocShell::GetSameTypeParent(nsIDocShellTreeItem** aParent)
 }
 
 NS_IMETHODIMP
-nsDocShell::GetSameTypeParentIgnoreBrowserAndAppBoundaries(nsIDocShell** aParent)
+nsDocShell::GetSameTypeParentIgnoreBrowserBoundaries(nsIDocShell** aParent)
 {
   NS_ENSURE_ARG_POINTER(aParent);
   *aParent = nullptr;
@@ -3504,18 +3504,18 @@ nsDocShell::GetSameTypeRootTreeItem(nsIDocShellTreeItem** aRootTreeItem)
 }
 
 NS_IMETHODIMP
-nsDocShell::GetSameTypeRootTreeItemIgnoreBrowserAndAppBoundaries(nsIDocShell ** aRootTreeItem)
+nsDocShell::GetSameTypeRootTreeItemIgnoreBrowserBoundaries(nsIDocShell** aRootTreeItem)
 {
     NS_ENSURE_ARG_POINTER(aRootTreeItem);
     *aRootTreeItem = static_cast<nsIDocShell *>(this);
 
     nsCOMPtr<nsIDocShell> parent;
-    NS_ENSURE_SUCCESS(GetSameTypeParentIgnoreBrowserAndAppBoundaries(getter_AddRefs(parent)),
+    NS_ENSURE_SUCCESS(GetSameTypeParentIgnoreBrowserBoundaries(getter_AddRefs(parent)),
                       NS_ERROR_FAILURE);
     while (parent) {
       *aRootTreeItem = parent;
       NS_ENSURE_SUCCESS((*aRootTreeItem)->
-        GetSameTypeParentIgnoreBrowserAndAppBoundaries(getter_AddRefs(parent)),
+        GetSameTypeParentIgnoreBrowserBoundaries(getter_AddRefs(parent)),
         NS_ERROR_FAILURE);
     }
     NS_ADDREF(*aRootTreeItem);
@@ -3570,8 +3570,7 @@ nsDocShell::CanAccessItem(nsIDocShellTreeItem* aTargetItem,
   }
 
   if (targetDS->GetIsInIsolatedMozBrowserElement() !=
-        accessingDS->GetIsInIsolatedMozBrowserElement() ||
-      targetDS->GetAppId() != accessingDS->GetAppId()) {
+        accessingDS->GetIsInIsolatedMozBrowserElement()) {
     return false;
   }
 
@@ -3595,7 +3594,7 @@ nsDocShell::CanAccessItem(nsIDocShellTreeItem* aTargetItem,
   if (OriginAttributes::IsFirstPartyEnabled()) {
     if (accessingDS == accessingRootDS &&
         aAccessingItem->ItemType() == nsIDocShellTreeItem::typeContent &&
-        !accessingDS->GetIsMozBrowserOrApp()) {
+        !accessingDS->GetIsMozBrowser()) {
 
       nsCOMPtr<nsIDocument> accessingDoc = aAccessingItem->GetDocument();
 
@@ -3609,7 +3608,7 @@ nsDocShell::CanAccessItem(nsIDocShellTreeItem* aTargetItem,
 
     if (targetDS == targetRootDS &&
         aTargetItem->ItemType() == nsIDocShellTreeItem::typeContent &&
-        !targetDS->GetIsMozBrowserOrApp()) {
+        !targetDS->GetIsMozBrowser()) {
 
       nsCOMPtr<nsIDocument> targetDoc = aAccessingItem->GetDocument();
 
@@ -3806,7 +3805,7 @@ nsDocShell::DoFindItemWithName(const nsAString& aName,
 
     // If we have a same-type parent, respecting browser and app boundaries.
     // NOTE: Could use GetSameTypeParent if the issues described in bug 1310344 are fixed.
-    if (!GetIsMozBrowserOrApp() && parentAsTreeItem->ItemType() == mItemType) {
+    if (!GetIsMozBrowser() && parentAsTreeItem->ItemType() == mItemType) {
       return parentAsTreeItem->FindItemWithName(
         aName,
         static_cast<nsIDocShellTreeItem*>(this),
@@ -5369,23 +5368,13 @@ nsDocShell::LoadErrorPage(nsIURI* aURI, const char16_t* aURL,
   errorPageUrl.AppendLiteral("&f=");
   errorPageUrl.AppendASCII(frameType.get());
 
-  // Append the manifest URL if the error comes from an app.
-  nsString manifestURL;
-  nsresult rv = GetAppManifestURL(manifestURL);
-  if (manifestURL.Length() > 0) {
-    nsCString manifestParam;
-    SAFE_ESCAPE(manifestParam, NS_ConvertUTF16toUTF8(manifestURL), url_Path);
-    errorPageUrl.AppendLiteral("&m=");
-    errorPageUrl.AppendASCII(manifestParam.get());
-  }
-
   // netError.xhtml's getDescription only handles the "d" parameter at the
   // end of the URL, so append it last.
   errorPageUrl.AppendLiteral("&d=");
   errorPageUrl.AppendASCII(escapedDescription.get());
 
   nsCOMPtr<nsIURI> errorPageURI;
-  rv = NS_NewURI(getter_AddRefs(errorPageURI), errorPageUrl);
+  nsresult rv = NS_NewURI(getter_AddRefs(errorPageURI), errorPageUrl);
   NS_ENSURE_SUCCESS(rv, rv);
 
   return InternalLoad(errorPageURI, nullptr, false, nullptr,
@@ -6205,9 +6194,7 @@ nsDocShell::SetIsActive(bool aIsActive)
     mScriptGlobal->SetIsBackground(!aIsActive);
     if (nsCOMPtr<nsIDocument> doc = mScriptGlobal->GetExtantDoc()) {
       // Update orientation when the top-level browsing context becomes active.
-      // We make an exception for apps because they currently rely on
-      // orientation locks persisting across browsing contexts.
-      if (aIsActive && !GetIsApp()) {
+      if (aIsActive) {
         nsCOMPtr<nsIDocShellTreeItem> parent;
         GetSameTypeParent(getter_AddRefs(parent));
         if (!parent) {
@@ -6244,7 +6231,7 @@ nsDocShell::SetIsActive(bool aIsActive)
       continue;
     }
 
-    if (!docshell->GetIsMozBrowserOrApp()) {
+    if (!docshell->GetIsMozBrowser()) {
       docshell->SetIsActive(aIsActive);
     }
   }
@@ -10556,9 +10543,7 @@ nsDocShell::InternalLoad(nsIURI* aURI,
   // lock the orientation of the document to the document's default
   // orientation. We don't explicitly check for a top-level browsing context
   // here because orientation is only set on top-level browsing contexts.
-  // We make an exception for apps because they currently rely on
-  // orientation locks persisting across browsing contexts.
-  if (OrientationLock() != eScreenOrientation_None && !GetIsApp()) {
+  if (OrientationLock() != eScreenOrientation_None) {
 #ifdef DEBUG
     nsCOMPtr<nsIDocShellTreeItem> parent;
     GetSameTypeParent(getter_AddRefs(parent));
@@ -10911,7 +10896,7 @@ nsDocShell::DoURILoad(nsIURI* aURI,
   NeckoOriginAttributes neckoAttrs;
   bool isTopLevelDoc = aContentPolicyType == nsIContentPolicy::TYPE_DOCUMENT &&
                        mItemType == typeContent &&
-                       !GetIsMozBrowserOrApp();
+                       !GetIsMozBrowser();
   neckoAttrs.InheritFromDocShellToNecko(GetOriginAttributes(), isTopLevelDoc, aURI);
   rv = loadInfo->SetOriginAttributes(neckoAttrs);
   if (NS_WARN_IF(NS_FAILED(rv))) {
@@ -14238,16 +14223,9 @@ nsDocShell::GetFrameType(uint32_t* aFrameType)
 }
 
 /* [infallible] */ NS_IMETHODIMP
-nsDocShell::GetIsApp(bool* aIsApp)
+nsDocShell::GetIsMozBrowser(bool* aIsMozBrowser)
 {
-  *aIsApp = (mFrameType == FRAME_TYPE_APP);
-  return NS_OK;
-}
-
-/* [infallible] */ NS_IMETHODIMP
-nsDocShell::GetIsMozBrowserOrApp(bool* aIsMozBrowserOrApp)
-{
-  *aIsMozBrowserOrApp = (mFrameType != FRAME_TYPE_REGULAR);
+  *aIsMozBrowser = (mFrameType == FRAME_TYPE_BROWSER);
   return NS_OK;
 }
 
@@ -14291,9 +14269,9 @@ nsDocShell::GetIsInIsolatedMozBrowserElement(bool* aIsInIsolatedMozBrowserElemen
 }
 
 /* [infallible] */ NS_IMETHODIMP
-nsDocShell::GetIsInMozBrowserOrApp(bool* aIsInMozBrowserOrApp)
+nsDocShell::GetIsInMozBrowser(bool* aIsInMozBrowser)
 {
-  *aIsInMozBrowserOrApp = (GetInheritedFrameType() != FRAME_TYPE_REGULAR);
+  *aIsInMozBrowser = (GetInheritedFrameType() == FRAME_TYPE_BROWSER);
   return NS_OK;
 }
 
@@ -14311,25 +14289,6 @@ nsDocShell::GetIsTopLevelContentDocShell(bool* aIsTopLevelContentDocShell)
   return NS_OK;
 }
 
-/* [infallible] */ NS_IMETHODIMP
-nsDocShell::GetAppId(uint32_t* aAppId)
-{
-  if (mOriginAttributes.mAppId != nsIScriptSecurityManager::UNKNOWN_APP_ID) {
-    *aAppId = mOriginAttributes.mAppId;
-    return NS_OK;
-  }
-
-  nsCOMPtr<nsIDocShell> parent;
-  GetSameTypeParentIgnoreBrowserAndAppBoundaries(getter_AddRefs(parent));
-
-  if (!parent) {
-    *aAppId = nsIScriptSecurityManager::NO_APP_ID;
-    return NS_OK;
-  }
-
-  return parent->GetAppId(aAppId);
-}
-
 // Implements nsILoadContext.originAttributes
 NS_IMETHODIMP
 nsDocShell::GetOriginAttributes(JS::MutableHandle<JS::Value> aVal)
@@ -14426,23 +14385,6 @@ nsDocShell::SetOriginAttributes(JS::Handle<JS::Value> aOriginAttributes,
   return SetOriginAttributes(attrs);
 }
 
-NS_IMETHODIMP
-nsDocShell::GetAppManifestURL(nsAString& aAppManifestURL)
-{
-  uint32_t appId = nsIDocShell::GetAppId();
-  if (appId != nsIScriptSecurityManager::NO_APP_ID &&
-      appId != nsIScriptSecurityManager::UNKNOWN_APP_ID) {
-    nsCOMPtr<nsIAppsService> appsService =
-      do_GetService(APPS_SERVICE_CONTRACTID);
-    NS_ASSERTION(appsService, "No AppsService available");
-    appsService->GetManifestURLByLocalId(appId, aAppManifestURL);
-  } else {
-    aAppManifestURL.SetLength(0);
-  }
-
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 nsDocShell::GetAsyncPanZoomEnabled(bool* aOut)
 {
diff --git a/docshell/base/nsDocShell.h b/docshell/base/nsDocShell.h
index 6617c7909c64..7c4282c9bcf3 100644
--- a/docshell/base/nsDocShell.h
+++ b/docshell/base/nsDocShell.h
@@ -779,8 +779,6 @@ protected:
   static const nsCString FrameTypeToString(uint32_t aFrameType)
   {
     switch (aFrameType) {
-      case FRAME_TYPE_APP:
-        return NS_LITERAL_CSTRING("app");
       case FRAME_TYPE_BROWSER:
         return NS_LITERAL_CSTRING("browser");
       case FRAME_TYPE_REGULAR:
diff --git a/docshell/base/nsIDocShell.idl b/docshell/base/nsIDocShell.idl
index 8261c45dcba2..7193fd379b31 100644
--- a/docshell/base/nsIDocShell.idl
+++ b/docshell/base/nsIDocShell.idl
@@ -792,34 +792,28 @@ interface nsIDocShell : nsIDocShellTreeItem
    */
   [noscript] void notifyScrollObservers();
 
-  /**
-   * Returns true iff the docshell corresponds to an <iframe mozapp>.
-   */
-  [infallible] readonly attribute boolean isApp;
-
   /**
    * The type of iframe that this docshell lives.
    */
   const unsigned long FRAME_TYPE_REGULAR = 0;
   const unsigned long FRAME_TYPE_BROWSER = 1;
-  const unsigned long FRAME_TYPE_APP     = 2;
 
   [infallible] attribute unsigned long frameType;
 
   /**
-   * Returns true if this docshell corresponds to an <iframe mozbrowser> or
-   * <iframe mozapp>.  <xul:browser> returns false here.
+   * Returns true if this docshell corresponds to an <iframe mozbrowser>.
+   * <xul:browser> returns false here.
    */
-  [infallible] readonly attribute boolean isMozBrowserOrApp;
+  [infallible] readonly attribute boolean isMozBrowser;
 
   /**
    * Returns true if this docshell corresponds to an isolated <iframe
    * mozbrowser>.
    *
-   * <iframe mozbrowser mozapp> and <xul:browser> are not considered to be
-   * mozbrowser elements.  <iframe mozbrowser noisolation> does not count as
-   * isolated since isolation is disabled.  Isolation can only be disabled if
-   * the containing document is chrome.
+   * <xul:browser> is not considered to be a mozbrowser element.
+   * <iframe mozbrowser noisolation> does not count as isolated since
+   * isolation is disabled.  Isolation can only be disabled if the
+   * containing document is chrome.
    */
   [infallible] readonly attribute boolean isIsolatedMozBrowserElement;
 
@@ -828,69 +822,45 @@ interface nsIDocShell : nsIDocShellTreeItem
    * mozbrowser> or if the docshell is contained in an isolated <iframe
    * mozbrowser>.
    *
-   * <iframe mozbrowser mozapp> and <xul:browser> are not considered to be
-   * mozbrowser elements.  <iframe mozbrowser noisolation> does not count as
-   * isolated since isolation is disabled.  Isolation can only be disabled if
-   * the containing document is chrome.
+   * <xul:browser> is not considered to be a mozbrowser element. <iframe
+   * mozbrowser noisolation> does not count as isolated since isolation is
+   * disabled.  Isolation can only be disabled if the containing document is
+   * chrome.
    *
    * Our notion here of "contained in" means: Walk up the docshell hierarchy in
-   * this process until we hit an <iframe mozapp> or <iframe mozbrowser> (or
-   * until the hierarchy ends).  Return true iff the docshell we stopped on has
+   * this process until we hit an <iframe mozbrowser> (or until the hierarchy
+   * ends).  Return true iff the docshell we stopped on has
    * isIsolatedMozBrowserElement == true.
    */
   [infallible] readonly attribute boolean isInIsolatedMozBrowserElement;
 
   /**
-   * Returns true if this docshell corresponds to an <iframe mozbrowser> or
-   * <iframe mozapp>, or if this docshell is contained in an <iframe mozbrowser>
-   * or <iframe mozapp>.  <xul:browser> returns false here.
+   * Returns true if this docshell corresponds to an <iframe mozbrowser>, or
+   * if this docshell is contained in an <iframe mozbrowser>. <xul:browser>
+   * returns false here.
    *
    * To compute this value, we walk up the docshell hierarchy.  If we encounter
-   * a docshell with isMozBrowserOrApp before we hit the end of the hierarchy,
+   * a docshell with isMozBrowser before we hit the end of the hierarchy,
    * we return true.  Otherwise, we return false.
    */
-  [infallible] readonly attribute boolean isInMozBrowserOrApp;
+  [infallible] readonly attribute boolean isInMozBrowser;
 
   /**
    * Returns true if this docshell is the top level content docshell.
    */
   [infallible] readonly attribute boolean isTopLevelContentDocShell;
 
-  /**
-   * Returns the id of the app associated with this docshell.  If this docshell
-   * is an <iframe mozbrowser> inside an <iframe mozapp>, we return the app's
-   * appId.
-   *
-   * We compute this value by walking up the docshell hierarchy until we find a
-   * docshell on which origin attributes was set. (ignoring those docshells
-   * where x == UNKNOWN_APP_ID).  We return the app id x.
-   *
-   * If we don't find a docshell with an associated app id in our hierarchy, we
-   * return NO_APP_ID.  We never return UNKNOWN_APP_ID.
-   *
-   * Notice that a docshell may have an associated app even if it returns true
-   * for isBrowserElement!
-   */
-  [infallible] readonly attribute unsigned long appId;
-
-  /**
-   * Return the manifest URL of the app associated with this docshell.
-   *
-   * If there is no associated app in our hierarchy, we return empty string.
-   */
-  readonly attribute DOMString appManifestURL;
-
   /**
    * Like nsIDocShellTreeItem::GetSameTypeParent, except this ignores <iframe
-   * mozbrowser> and <iframe mozapp> boundaries.
+   * mozbrowser> boundaries.
    */
-  nsIDocShell getSameTypeParentIgnoreBrowserAndAppBoundaries();
+  nsIDocShell getSameTypeParentIgnoreBrowserBoundaries();
 
   /**
    * Like nsIDocShellTreeItem::GetSameTypeRootTreeItem, except this ignores
-   * <iframe mozbrowser> and <iframe mozapp> boundaries.
+   * <iframe mozbrowser> boundaries.
    */
-  nsIDocShell getSameTypeRootTreeItemIgnoreBrowserAndAppBoundaries();
+  nsIDocShell getSameTypeRootTreeItemIgnoreBrowserBoundaries();
 
   /**
    * True iff asynchronous panning and zooming is enabled for this
diff --git a/docshell/base/nsIDocShellTreeItem.idl b/docshell/base/nsIDocShellTreeItem.idl
index 431b16c7970c..e2a3168f32b2 100644
--- a/docshell/base/nsIDocShellTreeItem.idl
+++ b/docshell/base/nsIDocShellTreeItem.idl
@@ -57,10 +57,9 @@ interface nsIDocShellTreeItem : nsISupports
 
 	/*
 	This getter returns the same thing parent does however if the parent
-	is of a different itemType, or if the parent is an <iframe mozbrowser>
-	or <iframe mozapp>, it will instead return nullptr.  This call is a
-	convience function for those wishing to not cross the boundaries at
-	which item types change.
+	is of a different itemType, or if the parent is an <iframe mozbrowser>.
+	It will instead return nullptr.  This call is a convience function for
+	Ithose wishing to not cross the boundaries at which item types change.
 	*/
 	readonly attribute nsIDocShellTreeItem sameTypeParent;
 
diff --git a/docshell/base/nsILoadContext.idl b/docshell/base/nsILoadContext.idl
index e1c367a81612..0284126ada3b 100644
--- a/docshell/base/nsILoadContext.idl
+++ b/docshell/base/nsILoadContext.idl
@@ -106,19 +106,13 @@ interface nsILoadContext : nsISupports
 
   /**
    * Returns true iff the load is occurring inside an isolated mozbrowser
-   * element. <iframe mozbrowser mozapp> and <xul:browser> are not considered to
-   * be mozbrowser elements.  <iframe mozbrowser noisolation> does not count as
-   * isolated since isolation is disabled.  Isolation can only be disabled if
-   * the containing document is chrome.
+   * element. <xul:browser> is not considered to be a mozbrowser element.
+   * <iframe mozbrowser noisolation> does not count as isolated since
+   * isolation is disabled.  Isolation can only be disabled if the
+   * containing document is chrome.
    */
   readonly attribute boolean isInIsolatedMozBrowserElement;
 
-  /**
-   * Returns the app id of the app the load is occurring is in. Returns
-   * nsIScriptSecurityManager::NO_APP_ID if the load is not part of an app.
-   */
-  readonly attribute unsigned long appId;
-
   /**
    * A dictionary of the non-default origin attributes associated with this
    * nsILoadContext.
diff --git a/dom/apps/PermissionsTable.jsm b/dom/apps/PermissionsTable.jsm
index 7c6a8490fc5e..550d73d6c796 100644
--- a/dom/apps/PermissionsTable.jsm
+++ b/dom/apps/PermissionsTable.jsm
@@ -233,11 +233,6 @@ this.PermissionsTable =  { geolocation: {
                              privileged: DENY_ACTION,
                              certified: ALLOW_ACTION
                            },
-                           "embed-apps": {
-                             app: DENY_ACTION,
-                             privileged: DENY_ACTION,
-                             certified: ALLOW_ACTION
-                           },
                            "background-sensors": {
                              app: DENY_ACTION,
                              privileged: DENY_ACTION,
diff --git a/dom/base/Navigator.cpp b/dom/base/Navigator.cpp
index 0b85394d7aba..811b17f03865 100644
--- a/dom/base/Navigator.cpp
+++ b/dom/base/Navigator.cpp
@@ -68,7 +68,6 @@
 #include "DeviceStorage.h"
 #include "nsStreamUtils.h"
 #include "nsIAppsService.h"
-#include "mozIApplication.h"
 #include "WidgetUtils.h"
 #include "nsIPresentationService.h"
 
diff --git a/dom/base/ThirdPartyUtil.cpp b/dom/base/ThirdPartyUtil.cpp
index 61d97f63488e..49e2416ad5f6 100644
--- a/dom/base/ThirdPartyUtil.cpp
+++ b/dom/base/ThirdPartyUtil.cpp
@@ -17,6 +17,7 @@
 #include "nsIURI.h"
 #include "nsThreadUtils.h"
 #include "mozilla/Logging.h"
+#include "nsPIDOMWindow.h"
 
 NS_IMPL_ISUPPORTS(ThirdPartyUtil, mozIThirdPartyUtil)
 
@@ -145,7 +146,7 @@ ThirdPartyUtil::IsThirdPartyWindow(mozIDOMWindowProxy* aWindow,
   nsCOMPtr<nsIURI> parentURI;
   do {
     // We use GetScriptableParent rather than GetParent because we consider
-    // <iframe mozbrowser/mozapp> to be a top-level frame.
+    // <iframe mozbrowser> to be a top-level frame.
     parent = current->GetScriptableParent();
     if (SameCOMIdentity(parent, current)) {
       // We're at the topmost content window. We already know the answer.
diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 98a553b68a75..54001d7d71d6 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -6400,7 +6400,7 @@ nsContentUtils::IsUserFocusIgnored(nsINode* aNode)
     nsCOMPtr<nsIMozBrowserFrame> browserFrame = do_QueryInterface(aNode);
     if (browserFrame &&
         aNode->AsElement()->HasAttr(kNameSpaceID_None, nsGkAtoms::ignoreuserfocus) &&
-        browserFrame->GetReallyIsBrowserOrApp()) {
+        browserFrame->GetReallyIsBrowser()) {
       return true;
     }
     nsPIDOMWindowOuter* win = aNode->OwnerDoc()->GetWindow();
diff --git a/dom/base/nsFrameLoader.cpp b/dom/base/nsFrameLoader.cpp
index 9fc53c0044fb..2ba00211e4a3 100644
--- a/dom/base/nsFrameLoader.cpp
+++ b/dom/base/nsFrameLoader.cpp
@@ -13,7 +13,6 @@
 
 #include "prenv.h"
 
-#include "mozIApplication.h"
 #include "nsDocShell.h"
 #include "nsIAppsService.h"
 #include "nsIDOMHTMLIFrameElement.h"
@@ -89,7 +88,6 @@
 #include "mozilla/dom/Element.h"
 #include "mozilla/jsipc/CrossProcessObjectWrappers.h"
 #include "mozilla/layout/RenderFrameParent.h"
-#include "nsIAppsService.h"
 #include "GeckoProfiler.h"
 
 #include "jsapi.h"
@@ -1066,8 +1064,7 @@ nsFrameLoader::SwapWithOtherRemoteLoader(nsFrameLoader* aOther,
   }
 
   if (mRemoteBrowser->IsIsolatedMozBrowserElement() !=
-      aOther->mRemoteBrowser->IsIsolatedMozBrowserElement() ||
-      mRemoteBrowser->HasOwnApp() != aOther->mRemoteBrowser->HasOwnApp()) {
+      aOther->mRemoteBrowser->IsIsolatedMozBrowserElement()) {
     return NS_ERROR_NOT_IMPLEMENTED;
   }
 
@@ -1139,10 +1136,10 @@ nsFrameLoader::SwapWithOtherRemoteLoader(nsFrameLoader* aOther,
   }
 
   // Destroy browser frame scripts for content leaving a frame with browser API
-  if (OwnerIsMozBrowserOrAppFrame() && !aOther->OwnerIsMozBrowserOrAppFrame()) {
+  if (OwnerIsMozBrowserFrame() && !aOther->OwnerIsMozBrowserFrame()) {
     DestroyBrowserFrameScripts();
   }
-  if (!OwnerIsMozBrowserOrAppFrame() && aOther->OwnerIsMozBrowserOrAppFrame()) {
+  if (!OwnerIsMozBrowserFrame() && aOther->OwnerIsMozBrowserFrame()) {
     aOther->DestroyBrowserFrameScripts();
   }
 
@@ -1314,12 +1311,12 @@ nsFrameLoader::SwapWithOtherLoader(nsFrameLoader* aOther,
 
   bool ourFullscreenAllowed =
     ourContent->IsXULElement() ||
-    (OwnerIsMozBrowserOrAppFrame() &&
+    (OwnerIsMozBrowserFrame() &&
       (ourContent->HasAttr(kNameSpaceID_None, nsGkAtoms::allowfullscreen) ||
        ourContent->HasAttr(kNameSpaceID_None, nsGkAtoms::mozallowfullscreen)));
   bool otherFullscreenAllowed =
     otherContent->IsXULElement() ||
-    (aOther->OwnerIsMozBrowserOrAppFrame() &&
+    (aOther->OwnerIsMozBrowserFrame() &&
       (otherContent->HasAttr(kNameSpaceID_None, nsGkAtoms::allowfullscreen) ||
        otherContent->HasAttr(kNameSpaceID_None, nsGkAtoms::mozallowfullscreen)));
   if (ourFullscreenAllowed != otherFullscreenAllowed) {
@@ -1465,8 +1462,7 @@ nsFrameLoader::SwapWithOtherLoader(nsFrameLoader* aOther,
   }
 
   if (ourDocshell->GetIsIsolatedMozBrowserElement() !=
-      otherDocshell->GetIsIsolatedMozBrowserElement() ||
-      ourDocshell->GetIsApp() != otherDocshell->GetIsApp()) {
+      otherDocshell->GetIsIsolatedMozBrowserElement()) {
     return NS_ERROR_NOT_IMPLEMENTED;
   }
 
@@ -1516,10 +1512,10 @@ nsFrameLoader::SwapWithOtherLoader(nsFrameLoader* aOther,
   }
 
   // Destroy browser frame scripts for content leaving a frame with browser API
-  if (OwnerIsMozBrowserOrAppFrame() && !aOther->OwnerIsMozBrowserOrAppFrame()) {
+  if (OwnerIsMozBrowserFrame() && !aOther->OwnerIsMozBrowserFrame()) {
     DestroyBrowserFrameScripts();
   }
-  if (!OwnerIsMozBrowserOrAppFrame() && aOther->OwnerIsMozBrowserOrAppFrame()) {
+  if (!OwnerIsMozBrowserFrame() && aOther->OwnerIsMozBrowserFrame()) {
     aOther->DestroyBrowserFrameScripts();
   }
 
@@ -1878,33 +1874,20 @@ nsFrameLoader::SetOwnerContent(Element* aContent)
 }
 
 bool
-nsFrameLoader::OwnerIsMozBrowserOrAppFrame()
+nsFrameLoader::OwnerIsMozBrowserFrame()
 {
   nsCOMPtr<nsIMozBrowserFrame> browserFrame = do_QueryInterface(mOwnerContent);
-  return browserFrame ? browserFrame->GetReallyIsBrowserOrApp() : false;
+  return browserFrame ? browserFrame->GetReallyIsBrowser() : false;
 }
 
 // The xpcom getter version
 NS_IMETHODIMP
-nsFrameLoader::GetOwnerIsMozBrowserOrAppFrame(bool* aResult)
+nsFrameLoader::GetOwnerIsMozBrowserFrame(bool* aResult)
 {
-  *aResult = OwnerIsMozBrowserOrAppFrame();
+  *aResult = OwnerIsMozBrowserFrame();
   return NS_OK;
 }
 
-bool
-nsFrameLoader::OwnerIsAppFrame()
-{
-  nsCOMPtr<nsIMozBrowserFrame> browserFrame = do_QueryInterface(mOwnerContent);
-  return browserFrame ? browserFrame->GetReallyIsApp() : false;
-}
-
-bool
-nsFrameLoader::OwnerIsMozBrowserFrame()
-{
-  return OwnerIsMozBrowserOrAppFrame() && !OwnerIsAppFrame();
-}
-
 bool
 nsFrameLoader::OwnerIsIsolatedMozBrowserFrame()
 {
@@ -1925,55 +1908,6 @@ nsFrameLoader::OwnerIsIsolatedMozBrowserFrame()
   return false;
 }
 
-void
-nsFrameLoader::GetOwnerAppManifestURL(nsAString& aOut)
-{
-  aOut.Truncate();
-  nsCOMPtr<nsIMozBrowserFrame> browserFrame = do_QueryInterface(mOwnerContent);
-  if (browserFrame) {
-    browserFrame->GetAppManifestURL(aOut);
-  }
-}
-
-already_AddRefed<mozIApplication>
-nsFrameLoader::GetOwnApp()
-{
-  nsAutoString manifest;
-  GetOwnerAppManifestURL(manifest);
-  if (manifest.IsEmpty()) {
-    return nullptr;
-  }
-
-  nsCOMPtr<nsIAppsService> appsService = do_GetService(APPS_SERVICE_CONTRACTID);
-  NS_ENSURE_TRUE(appsService, nullptr);
-
-  nsCOMPtr<mozIApplication> app;
-  appsService->GetAppByManifestURL(manifest, getter_AddRefs(app));
-
-  return app.forget();
-}
-
-already_AddRefed<mozIApplication>
-nsFrameLoader::GetContainingApp()
-{
-  // See if our owner content's principal has an associated app.
-  uint32_t appId = mOwnerContent->NodePrincipal()->GetAppId();
-  MOZ_ASSERT(appId != nsIScriptSecurityManager::UNKNOWN_APP_ID);
-
-  if (appId == nsIScriptSecurityManager::NO_APP_ID ||
-      appId == nsIScriptSecurityManager::UNKNOWN_APP_ID) {
-    return nullptr;
-  }
-
-  nsCOMPtr<nsIAppsService> appsService = do_GetService(APPS_SERVICE_CONTRACTID);
-  NS_ENSURE_TRUE(appsService, nullptr);
-
-  nsCOMPtr<mozIApplication> app;
-  appsService->GetAppByLocalId(appId, getter_AddRefs(app));
-
-  return app.forget();
-}
-
 bool
 nsFrameLoader::ShouldUseRemoteProcess()
 {
@@ -1997,7 +1931,7 @@ nsFrameLoader::ShouldUseRemoteProcess()
 
   // If we're an <iframe mozbrowser> and we don't have a "remote" attribute,
   // fall back to the default.
-  if (OwnerIsMozBrowserOrAppFrame() &&
+  if (OwnerIsMozBrowserFrame() &&
       !mOwnerContent->HasAttr(kNameSpaceID_None, nsGkAtoms::Remote)) {
 
     return Preferences::GetBool("dom.ipc.browser_frames.oop_by_default", false);
@@ -2005,7 +1939,7 @@ nsFrameLoader::ShouldUseRemoteProcess()
 
   // Otherwise, we're remote if we have "remote=true" and we're either a
   // browser frame or a XUL element.
-  return (OwnerIsMozBrowserOrAppFrame() ||
+  return (OwnerIsMozBrowserFrame() ||
           mOwnerContent->GetNameSpaceID() == kNameSpaceID_XUL) &&
          mOwnerContent->AttrValueIs(kNameSpaceID_None,
                                     nsGkAtoms::Remote,
@@ -2183,13 +2117,13 @@ nsFrameLoader::MaybeCreateDocShell()
   // Inherit origin attributes from parent document if
   // 1. It's in a content docshell.
   // 2. its nodePrincipal is not a SystemPrincipal.
-  // 3. It's not a mozbrowser nor mozapp frame.
+  // 3. It's not a mozbrowser frame.
   //
   // For example, firstPartyDomain is computed from top-level document, it
   // doesn't exist in the top-level docshell.
   if (parentType == nsIDocShellTreeItem::typeContent &&
       !nsContentUtils::IsSystemPrincipal(doc->NodePrincipal()) &&
-      !OwnerIsMozBrowserOrAppFrame()) {
+      !OwnerIsMozBrowserFrame()) {
     PrincipalOriginAttributes poa = BasePrincipal::Cast(doc->NodePrincipal())->OriginAttributesRef();
 
     // Assert on the firstPartyDomain from top-level docshell should be empty
@@ -2212,33 +2146,8 @@ nsFrameLoader::MaybeCreateDocShell()
     attrs.InheritFromDocToChildDocShell(poa);
   }
 
-  if (OwnerIsAppFrame()) {
-    // You can't be both an app and a browser frame.
-    MOZ_ASSERT(!OwnerIsMozBrowserFrame());
-
-    nsCOMPtr<mozIApplication> ownApp = GetOwnApp();
-    MOZ_ASSERT(ownApp);
-    uint32_t ownAppId = nsIScriptSecurityManager::NO_APP_ID;
-    if (ownApp) {
-      NS_ENSURE_SUCCESS(ownApp->GetLocalId(&ownAppId), NS_ERROR_FAILURE);
-    }
-
-    attrs.mAppId = ownAppId;
-    mDocShell->SetFrameType(nsIDocShell::FRAME_TYPE_APP);
-  }
-
   if (OwnerIsMozBrowserFrame()) {
-    // You can't be both a browser and an app frame.
-    MOZ_ASSERT(!OwnerIsAppFrame());
-
-    nsCOMPtr<mozIApplication> containingApp = GetContainingApp();
-    uint32_t containingAppId = nsIScriptSecurityManager::NO_APP_ID;
-    if (containingApp) {
-      NS_ENSURE_SUCCESS(containingApp->GetLocalId(&containingAppId),
-                        NS_ERROR_FAILURE);
-    }
-
-    attrs.mAppId = containingAppId;
+    attrs.mAppId = nsIScriptSecurityManager::NO_APP_ID;
     attrs.mInIsolatedMozBrowser = OwnerIsIsolatedMozBrowserFrame();
     mDocShell->SetFrameType(nsIDocShell::FRAME_TYPE_BROWSER);
   }
@@ -2270,7 +2179,7 @@ nsFrameLoader::MaybeCreateDocShell()
   }
   attrs.SyncAttributesWithPrivateBrowsing(isPrivate);
 
-  if (OwnerIsMozBrowserOrAppFrame()) {
+  if (OwnerIsMozBrowserFrame()) {
     // For inproc frames, set the docshell properties.
     nsAutoString name;
     if (mOwnerContent->GetAttr(kNameSpaceID_None, nsGkAtoms::name, name)) {
@@ -2669,7 +2578,7 @@ nsFrameLoader::TryRemoteBrowser()
   }
 
   // <iframe mozbrowser> gets to skip these checks.
-  if (!OwnerIsMozBrowserOrAppFrame()) {
+  if (!OwnerIsMozBrowserFrame()) {
     if (parentDocShell->ItemType() != nsIDocShellTreeItem::typeChrome) {
       return false;
     }
@@ -2710,8 +2619,8 @@ nsFrameLoader::TryRemoteBrowser()
   NS_ENSURE_SUCCESS(rv, false);
 
   nsCOMPtr<Element> ownerElement = mOwnerContent;
-  mRemoteBrowser = ContentParent::CreateBrowserOrApp(context, ownerElement,
-                                                     openerContentParent, mFreshProcess);
+  mRemoteBrowser = ContentParent::CreateBrowser(context, ownerElement, openerContentParent,
+                                                mFreshProcess);
   if (!mRemoteBrowser) {
     return false;
   }
@@ -2974,7 +2883,7 @@ nsFrameLoader::EnsureMessageManager()
   }
 
   if (!mIsTopLevelContent &&
-      !OwnerIsMozBrowserOrAppFrame() &&
+      !OwnerIsMozBrowserFrame() &&
       !IsRemoteFrame() &&
       !(mOwnerContent->IsXULElement() &&
         mOwnerContent->AttrValueIs(kNameSpaceID_None,
@@ -3289,7 +3198,7 @@ nsFrameLoader::GetLoadContext(nsILoadContext** aLoadContext)
 void
 nsFrameLoader::InitializeBrowserAPI()
 {
-  if (!OwnerIsMozBrowserOrAppFrame()) {
+  if (!OwnerIsMozBrowserFrame()) {
     return;
   }
   if (!IsRemoteFrame()) {
@@ -3313,7 +3222,7 @@ nsFrameLoader::InitializeBrowserAPI()
 void
 nsFrameLoader::DestroyBrowserFrameScripts()
 {
-  if (!OwnerIsMozBrowserOrAppFrame()) {
+  if (!OwnerIsMozBrowserFrame()) {
     return;
   }
   nsCOMPtr<nsIMozBrowserFrame> browserFrame = do_QueryInterface(mOwnerContent);
@@ -3394,24 +3303,11 @@ nsresult
 nsFrameLoader::GetNewTabContext(MutableTabContext* aTabContext,
                                 nsIURI* aURI)
 {
-  nsCOMPtr<mozIApplication> ownApp = GetOwnApp();
-  nsCOMPtr<mozIApplication> containingApp = GetContainingApp();
   DocShellOriginAttributes attrs;
   attrs.mInIsolatedMozBrowser = OwnerIsIsolatedMozBrowserFrame();
   nsresult rv;
 
-  // Get the AppId from ownApp
-  uint32_t appId = nsIScriptSecurityManager::NO_APP_ID;
-  if (ownApp) {
-    rv = ownApp->GetLocalId(&appId);
-    NS_ENSURE_SUCCESS(rv, rv);
-    NS_ENSURE_STATE(appId != nsIScriptSecurityManager::NO_APP_ID);
-  } else if (containingApp) {
-    rv = containingApp->GetLocalId(&appId);
-    NS_ENSURE_SUCCESS(rv, rv);
-    NS_ENSURE_STATE(appId != nsIScriptSecurityManager::NO_APP_ID);
-  }
-  attrs.mAppId = appId;
+  attrs.mAppId = nsIScriptSecurityManager::NO_APP_ID;
 
   // set the userContextId on the attrs before we pass them into
   // the tab context
@@ -3446,8 +3342,6 @@ nsFrameLoader::GetNewTabContext(MutableTabContext* aTabContext,
   bool tabContextUpdated =
     aTabContext->SetTabContext(OwnerIsMozBrowserFrame(),
                                mIsPrerendered,
-                               ownApp,
-                               containingApp,
                                showAccelerators,
                                showFocusRings,
                                attrs,
diff --git a/dom/base/nsFrameLoader.h b/dom/base/nsFrameLoader.h
index bbbd52f58fbd..3292b17302f9 100644
--- a/dom/base/nsFrameLoader.h
+++ b/dom/base/nsFrameLoader.h
@@ -36,7 +36,6 @@ class AutoResetInFrameSwap;
 class nsITabParent;
 class nsIDocShellTreeItem;
 class nsIDocShellTreeOwner;
-class mozIApplication;
 
 namespace mozilla {
 
@@ -242,20 +241,6 @@ private:
    */
   bool IsRemoteFrame();
 
-  /**
-   * Is this a frameloader for a bona fide <iframe mozbrowser> or
-   * <iframe mozapp>?  (I.e., does the frame return true for
-   * nsIMozBrowserFrame::GetReallyIsBrowserOrApp()?)
-   * <xul:browser> is not a mozbrowser or app, so this is false for that case.
-   */
-  bool OwnerIsMozBrowserOrAppFrame();
-
-  /**
-   * Is this a frameloader for a bona fide <iframe mozapp>?  (I.e., does the
-   * frame return true for nsIMozBrowserFrame::GetReallyIsApp()?)
-   */
-  bool OwnerIsAppFrame();
-
   /**
    * Is this a frame loader for a bona fide <iframe mozbrowser>?
    * <xul:browser> is not a mozbrowser, so this is false for that case.
@@ -277,18 +262,6 @@ private:
    */
   void GetOwnerAppManifestURL(nsAString& aOut);
 
-  /**
-   * Get the app for our frame.  This is the app whose manifest is returned by
-   * GetOwnerAppManifestURL.
-   */
-  already_AddRefed<mozIApplication> GetOwnApp();
-
-  /**
-   * Get the app which contains this frame.  This is the app associated with
-   * the frame element's principal.
-   */
-  already_AddRefed<mozIApplication> GetContainingApp();
-
   /**
    * If we are an IPC frame, set mRemoteFrame. Otherwise, create and
    * initialize mDocShell.
diff --git a/dom/base/nsGkAtomList.h b/dom/base/nsGkAtomList.h
index 7827ad66b6fe..0292ad1abbac 100644
--- a/dom/base/nsGkAtomList.h
+++ b/dom/base/nsGkAtomList.h
@@ -101,7 +101,6 @@ GK_ATOM(animations, "animations")
 GK_ATOM(anonid, "anonid")
 GK_ATOM(anonlocation, "anonlocation")
 GK_ATOM(any, "any")
-GK_ATOM(mozapp, "mozapp")
 GK_ATOM(applet, "applet")
 GK_ATOM(applyImports, "apply-imports")
 GK_ATOM(applyTemplates, "apply-templates")
@@ -992,7 +991,6 @@ GK_ATOM(panel, "panel")
 GK_ATOM(param, "param")
 GK_ATOM(parameter, "parameter")
 GK_ATOM(parent, "parent")
-GK_ATOM(parentapp, "parentapp")
 GK_ATOM(parentfocused, "parentfocused")
 GK_ATOM(parsetype, "parsetype")
 GK_ATOM(password, "password")
diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index 8405f6ef3bb3..d140b63b1294 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -4200,7 +4200,7 @@ nsGlobalWindow::GetParentOuter()
   }
 
   nsCOMPtr<nsPIDOMWindowOuter> parent;
-  if (mDocShell->GetIsMozBrowserOrApp()) {
+  if (mDocShell->GetIsMozBrowser()) {
     parent = AsOuter();
   } else {
     parent = GetParent();
@@ -4258,7 +4258,7 @@ nsGlobalWindow::GetParent()
   }
 
   nsCOMPtr<nsIDocShell> parent;
-  mDocShell->GetSameTypeParentIgnoreBrowserAndAppBoundaries(getter_AddRefs(parent));
+  mDocShell->GetSameTypeParentIgnoreBrowserBoundaries(getter_AddRefs(parent));
 
   if (parent) {
     nsCOMPtr<nsPIDOMWindowOuter> win = parent->GetWindow();
@@ -4377,9 +4377,9 @@ nsGlobalWindow::GetContentInternal(ErrorResult& aError, bool aUnprivilegedCaller
     return domWindow.forget();
   }
 
-  // If we're contained in <iframe mozbrowser> or <iframe mozapp>, then
-  // GetContent is the same as window.top.
-  if (mDocShell && mDocShell->GetIsInMozBrowserOrApp()) {
+  // If we're contained in <iframe mozbrowser>, then GetContent is the same as
+  // window.top.
+  if (mDocShell && mDocShell->GetIsInMozBrowser()) {
     return GetTopOuter();
   }
 
@@ -7700,7 +7700,7 @@ nsGlobalWindow::ResizeToOuter(int32_t aWidth, int32_t aHeight, ErrorResult& aErr
    * If caller is a browser-element then dispatch a resize event to
    * the embedder.
    */
-  if (mDocShell && mDocShell->GetIsMozBrowserOrApp()) {
+  if (mDocShell && mDocShell->GetIsMozBrowser()) {
     CSSIntSize size(aWidth, aHeight);
     if (!DispatchResizeEvent(size)) {
       // The embedder chose to prevent the default action for this
@@ -7750,7 +7750,7 @@ nsGlobalWindow::ResizeByOuter(int32_t aWidthDif, int32_t aHeightDif,
    * If caller is a browser-element then dispatch a resize event to
    * parent.
    */
-  if (mDocShell && mDocShell->GetIsMozBrowserOrApp()) {
+  if (mDocShell && mDocShell->GetIsMozBrowser()) {
     CSSIntSize size;
     if (NS_FAILED(GetInnerSize(size))) {
       return;
@@ -8719,7 +8719,7 @@ nsGlobalWindow::CloseOuter(bool aTrustedCaller)
   MOZ_RELEASE_ASSERT(IsOuterWindow());
 
   if (!mDocShell || IsInModalState() ||
-      (IsFrame() && !mDocShell->GetIsMozBrowserOrApp())) {
+      (IsFrame() && !mDocShell->GetIsMozBrowser())) {
     // window.close() is called on a frame in a frameset, on a window
     // that's already closed, or on a window for which there's
     // currently a modal dialog open. Ignore such calls.
@@ -8740,14 +8740,13 @@ nsGlobalWindow::CloseOuter(bool aTrustedCaller)
     return;
   }
 
-  // Don't allow scripts from content to close non-app or non-neterror
-  // windows that were not opened by script.
+  // Don't allow scripts from content to close non-neterror windows that
+  // were not opened by script.
   nsAutoString url;
   nsresult rv = mDoc->GetURL(url);
   NS_ENSURE_SUCCESS_VOID(rv);
 
-  if (!mDocShell->GetIsApp() &&
-      !StringBeginsWith(url, NS_LITERAL_STRING("about:neterror")) &&
+  if (!StringBeginsWith(url, NS_LITERAL_STRING("about:neterror")) &&
       !mHadOriginalOpener && !aTrustedCaller) {
     bool allowClose = mAllowScriptsToClose ||
       Preferences::GetBool("dom.allow_scripts_to_close_windows", true);
@@ -9195,7 +9194,7 @@ nsGlobalWindow::GetFrameElementOuter(nsIPrincipal& aSubjectPrincipal)
 {
   MOZ_RELEASE_ASSERT(IsOuterWindow());
 
-  if (!mDocShell || mDocShell->GetIsMozBrowserOrApp()) {
+  if (!mDocShell || mDocShell->GetIsMozBrowser()) {
     return nullptr;
   }
 
@@ -9230,7 +9229,7 @@ nsGlobalWindow::GetRealFrameElementOuter()
   }
 
   nsCOMPtr<nsIDocShell> parent;
-  mDocShell->GetSameTypeParentIgnoreBrowserAndAppBoundaries(getter_AddRefs(parent));
+  mDocShell->GetSameTypeParentIgnoreBrowserBoundaries(getter_AddRefs(parent));
 
   if (!parent || parent == mDocShell) {
     // We're at a chrome boundary, don't expose the chrome iframe
diff --git a/dom/base/nsIFrameLoader.idl b/dom/base/nsIFrameLoader.idl
index d840cdce6396..d09dd934216e 100644
--- a/dom/base/nsIFrameLoader.idl
+++ b/dom/base/nsIFrameLoader.idl
@@ -5,7 +5,6 @@
 
 #include "nsISupports.idl"
 
-interface mozIApplication;
 interface nsFrameLoader;
 interface nsIDocShell;
 interface nsIURI;
@@ -216,11 +215,10 @@ interface nsIFrameLoader : nsISupports
   [infallible] attribute boolean visible;
 
   /**
-   * Find out whether the owner content really is a mozbrowser or app frame
-   * Especially, a widget frame is regarded as an app frame.  <xul:browser> is
-   * not considered to be a mozbrowser frame.
+   * Find out whether the owner content really is a mozbrowser. <xul:browser>
+   * is not considered to be a mozbrowser frame.
    */
-  readonly attribute boolean ownerIsMozBrowserOrAppFrame;
+  readonly attribute boolean ownerIsMozBrowserFrame;
 
   /**
    * The last known width of the frame. Reading this property will not trigger
@@ -265,12 +263,6 @@ interface nsIFrameLoaderOwner : nsISupports
   [binaryname(FrameLoaderXPCOM)] readonly attribute nsIFrameLoader frameLoader;
   [noscript, notxpcom] alreadyAddRefed_nsFrameLoader GetFrameLoader();
 
-  /**
-   * The principal of parent mozIApplication in case of nested mozbrowser
-   * iframes.
-   */
-  readonly attribute mozIApplication parentApplication;
-
   /**
    * Puts the FrameLoaderOwner in prerendering mode.
    */
diff --git a/dom/base/nsInProcessTabChildGlobal.cpp b/dom/base/nsInProcessTabChildGlobal.cpp
index 10ccf4aec3b2..94e4eb62ce85 100644
--- a/dom/base/nsInProcessTabChildGlobal.cpp
+++ b/dom/base/nsInProcessTabChildGlobal.cpp
@@ -96,14 +96,14 @@ nsInProcessTabChildGlobal::nsInProcessTabChildGlobal(nsIDocShell* aShell,
   SetIsNotDOMBinding();
   mozilla::HoldJSObjects(this);
 
-  // If owner corresponds to an <iframe mozbrowser> or <iframe mozapp>, we'll
-  // have to tweak our PreHandleEvent implementation.
+  // If owner corresponds to an <iframe mozbrowser>, we'll have to tweak our
+  // PreHandleEvent implementation.
   nsCOMPtr<nsIMozBrowserFrame> browserFrame = do_QueryInterface(mOwner);
   if (browserFrame) {
-    mIsBrowserOrAppFrame = browserFrame->GetReallyIsBrowserOrApp();
+    mIsBrowserFrame = browserFrame->GetReallyIsBrowser();
   }
   else {
-    mIsBrowserOrAppFrame = false;
+    mIsBrowserFrame = false;
   }
 }
 
@@ -274,7 +274,7 @@ nsInProcessTabChildGlobal::PreHandleEvent(EventChainPreVisitor& aVisitor)
     return NS_OK;
   }
 
-  if (mIsBrowserOrAppFrame &&
+  if (mIsBrowserFrame &&
       (!mOwner || !nsContentUtils::IsInChromeDocshell(mOwner->OwnerDoc()))) {
     if (mOwner) {
       if (nsPIDOMWindowInner* innerWindow = mOwner->OwnerDoc()->GetInnerWindow()) {
diff --git a/dom/base/nsInProcessTabChildGlobal.h b/dom/base/nsInProcessTabChildGlobal.h
index e7dd9cb5a63b..f56fd8dfd73f 100644
--- a/dom/base/nsInProcessTabChildGlobal.h
+++ b/dom/base/nsInProcessTabChildGlobal.h
@@ -166,10 +166,9 @@ protected:
   bool mInitialized;
   bool mLoadingScript;
 
-  // Is this the message manager for an in-process <iframe mozbrowser> or
-  // <iframe mozapp>?  This affects where events get sent, so it affects
-  // PreHandleEvent.
-  bool mIsBrowserOrAppFrame;
+  // Is this the message manager for an in-process <iframe mozbrowser>? This
+  // affects where events get sent, so it affects PreHandleEvent.
+  bool mIsBrowserFrame;
   bool mPreventEventsEscaping;
 
   // We keep a strong reference to the frameloader after we've started
diff --git a/dom/base/nsObjectLoadingContent.cpp b/dom/base/nsObjectLoadingContent.cpp
index f5c28c0a9c0f..613dae74dd57 100644
--- a/dom/base/nsObjectLoadingContent.cpp
+++ b/dom/base/nsObjectLoadingContent.cpp
@@ -1243,17 +1243,6 @@ nsObjectLoadingContent::GetFrameLoader()
   return loader.forget();
 }
 
-NS_IMETHODIMP
-nsObjectLoadingContent::GetParentApplication(mozIApplication** aApplication)
-{
-  if (!aApplication) {
-    return NS_ERROR_FAILURE;
-  }
-
-  *aApplication = nullptr;
-  return NS_OK;
-}
-
 void
 nsObjectLoadingContent::PresetOpenerWindow(mozIDOMWindowProxy* aWindow, mozilla::ErrorResult& aRv)
 {
diff --git a/dom/base/nsXHTMLContentSerializer.cpp b/dom/base/nsXHTMLContentSerializer.cpp
index 0dc31d7aec22..111ed46c7174 100644
--- a/dom/base/nsXHTMLContentSerializer.cpp
+++ b/dom/base/nsXHTMLContentSerializer.cpp
@@ -306,7 +306,7 @@ nsXHTMLContentSerializer::SerializeAttributes(nsIContent* aContent,
         continue;
     }
 
-    BorrowedAttrInfo info = aContent->GetAttrInfoAt(index);
+    mozilla::dom::BorrowedAttrInfo info = aContent->GetAttrInfoAt(index);
     const nsAttrName* name = info.mName;
 
     int32_t namespaceID = name->NamespaceID();
diff --git a/dom/browser-element/BrowserElementChild.js b/dom/browser-element/BrowserElementChild.js
index 066be66d20a6..a0921a660c87 100644
--- a/dom/browser-element/BrowserElementChild.js
+++ b/dom/browser-element/BrowserElementChild.js
@@ -26,7 +26,7 @@ function parentDocShell(docshell) {
 function isTopBrowserElement(docShell) {
   while (docShell) {
     docShell = parentDocShell(docShell);
-    if (docShell && docShell.isMozBrowserOrApp) {
+    if (docShell && docShell.isMozBrowser) {
       return false;
     }
   }
diff --git a/dom/browser-element/BrowserElementCopyPaste.js b/dom/browser-element/BrowserElementCopyPaste.js
index 7aa7c5148b5d..0f72768a87b2 100644
--- a/dom/browser-element/BrowserElementCopyPaste.js
+++ b/dom/browser-element/BrowserElementCopyPaste.js
@@ -113,7 +113,7 @@ var CopyPasteAssistent = {
       let targetDocShell = currentWindow
           .QueryInterface(Ci.nsIInterfaceRequestor)
           .getInterface(Ci.nsIWebNavigation);
-      if(targetDocShell.isMozBrowserOrApp) {
+      if(targetDocShell.isMozBrowser) {
         break;
       }
     }
diff --git a/dom/browser-element/BrowserElementParent.cpp b/dom/browser-element/BrowserElementParent.cpp
index fda9348fd1b1..fddd0de3d75c 100644
--- a/dom/browser-element/BrowserElementParent.cpp
+++ b/dom/browser-element/BrowserElementParent.cpp
@@ -55,23 +55,6 @@ CreateIframe(Element* aOpenerFrameElement, const nsAString& aName, bool aRemote)
 
   popupFrameElement->SetMozbrowser(true);
 
-  // Copy the opener frame's mozapp attribute to the popup frame.
-  if (aOpenerFrameElement->HasAttr(kNameSpaceID_None, nsGkAtoms::mozapp)) {
-    nsAutoString mozapp;
-    aOpenerFrameElement->GetAttr(kNameSpaceID_None, nsGkAtoms::mozapp, mozapp);
-    popupFrameElement->SetAttr(kNameSpaceID_None, nsGkAtoms::mozapp,
-                               mozapp, /* aNotify = */ false);
-  }
-
-  // Copy the opener frame's parentApp attribute to the popup frame.
-  if (aOpenerFrameElement->HasAttr(kNameSpaceID_None, nsGkAtoms::parentapp)) {
-    nsAutoString parentApp;
-    aOpenerFrameElement->GetAttr(kNameSpaceID_None, nsGkAtoms::parentapp,
-                                 parentApp);
-    popupFrameElement->SetAttr(kNameSpaceID_None, nsGkAtoms::parentapp,
-                               parentApp, /* aNotify = */ false);
-  }
-
   // Copy the window name onto the iframe.
   popupFrameElement->SetAttr(kNameSpaceID_None, nsGkAtoms::name,
                              aName, /* aNotify = */ false);
diff --git a/dom/browser-element/mochitest/browserElement_SetInputMethodActive.js b/dom/browser-element/mochitest/browserElement_SetInputMethodActive.js
index 9cc2f79a1ec5..6fe582dd9626 100644
--- a/dom/browser-element/mochitest/browserElement_SetInputMethodActive.js
+++ b/dom/browser-element/mochitest/browserElement_SetInputMethodActive.js
@@ -8,27 +8,6 @@
 SimpleTest.waitForExplicitFinish();
 browserElementTestHelpers.setEnabledPref(true);
 
-// We'll need to get the appId from the current document,
-// it's either SpecialPowers.Ci.nsIScriptSecurityManager.NO_APP_ID when
-// we are not running inside an app (e.g. Firefox Desktop),
-// or the appId of Mochitest app when we are running inside that app
-// (e.g. Emulator).
-var currentAppId = SpecialPowers.wrap(document).nodePrincipal.appId;
-var inApp =
-  currentAppId !== SpecialPowers.Ci.nsIScriptSecurityManager.NO_APP_ID;
-// We will also need the manifest URL and set it on iframes.
-var currentAppManifestURL;
-
-if (inApp) {
-  let appsService = SpecialPowers.Cc["@mozilla.org/AppsService;1"]
-                      .getService(SpecialPowers.Ci.nsIAppsService);
-
-  currentAppManifestURL = appsService.getManifestURLByLocalId(currentAppId);
-};
-
-info('appId=' + currentAppId);
-info('manifestURL=' + currentAppManifestURL);
-
 function setup() {
   let appInfo = SpecialPowers.Cc['@mozilla.org/xre/app-info;1']
                 .getService(SpecialPowers.Ci.nsIXULAppInfo);
@@ -73,9 +52,6 @@ function createFrames() {
    for (let i = 0; i < 2; i++) {
      let frame = gInputMethodFrames[i] = document.createElement('iframe');
      frame.setAttribute('mozbrowser', 'true');
-     if (currentAppManifestURL) {
-       frame.setAttribute('mozapp', currentAppManifestURL);
-     }
      frame.addEventListener('mozbrowserloadend', countLoadend);
      frame.src = 'file_empty.html#' + i;
      document.body.appendChild(frame);
@@ -89,19 +65,11 @@ function setPermissions() {
     context: {
       url: SimpleTest.getTestFileURL('/file_empty.html'),
       originAttributes: {
-        appId: currentAppId,
         inIsolatedMozBrowser: true
       }
     }
   }];
 
-  if (inApp) {
-    // The current document would also need to be given access for IPC to
-    // recognize our permission (why)?
-    permissions.push({
-      type: 'input', allow: true, context: document });
-  }
-
   SpecialPowers.pushPermissions(permissions,
     SimpleTest.waitForFocus.bind(SimpleTest, startTest));
 }
diff --git a/dom/browser-element/mochitest/file_browserElement_AudioChannel_nested.html b/dom/browser-element/mochitest/file_browserElement_AudioChannel_nested.html
index c37a642e2d7d..de3aab37e92f 100644
--- a/dom/browser-element/mochitest/file_browserElement_AudioChannel_nested.html
+++ b/dom/browser-element/mochitest/file_browserElement_AudioChannel_nested.html
@@ -20,7 +20,6 @@
     // set 'remote' to true here will make the the iframe remote in _inproc_
     // test and in-process in _oop_  test.
     iframe.setAttribute('remote', 'true');
-    iframe.setAttribute('mozapp', 'http://example.org/manifest.webapp');
 
     iframe.addEventListener('mozbrowserloadend', function(e) {
       ok("mute" in iframe, "iframe.mute exists");
diff --git a/dom/devicestorage/test/test_app_permissions.html b/dom/devicestorage/test/test_app_permissions.html
index 9d6ecad1900f..33cf34921c1f 100644
--- a/dom/devicestorage/test/test_app_permissions.html
+++ b/dom/devicestorage/test/test_app_permissions.html
@@ -197,48 +197,6 @@ var gData = [
     test: TestGet
   },
 
-  // Certified application with permision granted
-  {
-    type: 'pictures',
-    shouldPass: true,
-    fileExtension: '.png',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:pictures"],
-
-    test: TestGet
-  },
-  {
-    type: 'videos',
-    shouldPass: true,
-    fileExtension: '.ogv',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestGet
-  },
-  {
-    type: 'music',
-    shouldPass: true,
-    fileExtension: '.ogg',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestGet
-  },
-  {
-    type: 'sdcard',
-    shouldPass: true,
-    fileExtension: '.txt',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:sdcard"],
-
-    test: TestGet
-  },
-
 
   // Add
 
@@ -315,52 +273,6 @@ var gData = [
     test: TestAdd
   },
 
-  // Certified application with permision granted
-  {
-    type: 'pictures',
-    mimeType: 'image/png',
-    fileExtension: '.png',
-    shouldPass: true,
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:pictures"],
-
-    test: TestAdd
-  },
-  {
-    type: 'videos',
-    mimeType: 'video/ogv',
-    fileExtension: '.ogv',
-    shouldPass: true,
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestAdd
-  },
-  {
-    type: 'music',
-    mimeType: 'audio/ogg',
-    fileExtension: '.ogg',
-    shouldPass: true,
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestAdd
-  },
-  {
-    type: 'sdcard',
-    mimeType: 'text/plain',
-    fileExtension: '.txt',
-    shouldPass: true,
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:sdcard"],
-
-    test: TestAdd
-  },
-
 
 // Delete 
 
@@ -428,48 +340,6 @@ var gData = [
     test: TestDelete
   },
 
-  // Certified application with permision granted
-  {
-    type: 'pictures',
-    shouldPass: true,
-    fileExtension: '.png',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:pictures"],
-
-    test: TestDelete
-  },
-  {
-    type: 'videos',
-    shouldPass: true,
-    fileExtension: '.ogv',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestDelete
-  },
-  {
-    type: 'music',
-    shouldPass: true,
-    fileExtension: '.ogg',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestDelete
-  },
-  {
-    type: 'sdcard',
-    shouldPass: true,
-    fileExtension: '.txt',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:sdcard"],
-
-    test: TestDelete
-  },
-
 // Enumeration 
 
   // Web applications with no permissions
@@ -536,48 +406,6 @@ var gData = [
     test: TestEnumerate
   },
 
-  // Certified application with permision granted
-  {
-    type: 'pictures',
-    shouldPass: true,
-    fileExtension: '.png',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:pictures"],
-
-    test: TestEnumerate
-  },
-  {
-    type: 'videos',
-    shouldPass: true,
-    fileExtension: '.ogv',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestEnumerate
-  },
-  {
-    type: 'music',
-    shouldPass: true,
-    fileExtension: '.ogg',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestEnumerate
-  },
-  {
-    type: 'sdcard',
-    shouldPass: true,
-    fileExtension: '.txt',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:sdcard"],
-
-    test: TestEnumerate
-  },
-
 ];
 
 function setupTest(iframe,data) {
@@ -610,9 +438,6 @@ function runTest() {
     var data = gData.pop();
 
     iframe.setAttribute('mozbrowser', '');
-    if (data.app) {
-      iframe.setAttribute('mozapp', data.app);
-    }
 
     iframe.src = gTestUri;
 
diff --git a/dom/devicestorage/test/test_fs_app_permissions.html b/dom/devicestorage/test/test_fs_app_permissions.html
index 103b9b6cf71a..066ea2891063 100644
--- a/dom/devicestorage/test/test_fs_app_permissions.html
+++ b/dom/devicestorage/test/test_fs_app_permissions.html
@@ -262,68 +262,6 @@ let gData = [
     test: TestGet
   },
 
-  // Certified application with permision granted
-  {
-    type: 'pictures',
-    shouldPass: true,
-    fileExtension: '.png',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:pictures"],
-
-    test: TestGet
-  },
-  {
-    type: 'videos',
-    shouldPass: true,
-    fileExtension: '.ogv',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestGet
-  },
-  {
-    type: 'videos',
-    shouldPass: true,
-    fileExtension: '.ogg',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestGet
-  },
-  {
-    type: 'music',
-    shouldPass: true,
-    fileExtension: '.ogg',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestGet
-  },
-  {
-    type: 'music',
-    shouldPass: false,
-    fileExtension: '.txt',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestGet
-  },
-  {
-    type: 'sdcard',
-    shouldPass: true,
-    fileExtension: '.txt',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:sdcard"],
-
-    test: TestGet
-  },
-
   // Directory#createDirectory
 
   // Web applications with no permissions
@@ -382,44 +320,6 @@ let gData = [
     test: TestCreateDirectory
   },
 
-  // Certified application with permision granted
-  {
-    type: 'pictures',
-    shouldPass: true,
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:pictures"],
-
-    test: TestCreateDirectory
-  },
-  {
-    type: 'videos',
-    shouldPass: true,
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestCreateDirectory
-  },
-  {
-    type: 'music',
-    shouldPass: true,
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestCreateDirectory
-  },
-  {
-    type: 'sdcard',
-    shouldPass: true,
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:sdcard"],
-
-    test: TestCreateDirectory
-  },
-
   // Directory#createFile
 
   // Web applications with no permissions
@@ -528,74 +428,6 @@ let gData = [
     test: TestCreateFile
   },
 
-  // Certified application with permision granted
-  {
-    type: 'pictures',
-    mimeType: 'image/png',
-    shouldPass: true,
-    fileExtension: '.png',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:pictures"],
-
-    test: TestCreateFile
-  },
-  {
-    type: 'videos',
-    mimeType: 'video/ogv',
-    shouldPass: true,
-    fileExtension: '.ogv',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestCreateFile
-  },
-  {
-    type: 'videos',
-    mimeType: 'video/ogg',
-    shouldPass: true,
-    fileExtension: '.ogg',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestCreateFile
-  },
-  {
-    type: 'music',
-    mimeType: 'audio/ogg',
-    shouldPass: true,
-    fileExtension: '.ogg',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestCreateFile
-  },
-  {
-    type: 'music',
-    mimeType: 'audio/ogg',
-    shouldPass: false,
-    fileExtension: '.txt',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestCreateFile
-  },
-  {
-    type: 'sdcard',
-    mimeType: 'text/plain',
-    shouldPass: true,
-    fileExtension: '.txt',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:sdcard"],
-
-    test: TestCreateFile
-  },
-
   // Directory#remove
 
   // Web applications with no permissions
@@ -692,68 +524,6 @@ let gData = [
     test: TestRemove
   },
 
-  // Certified application with permision granted
-  {
-    type: 'pictures',
-    shouldPass: true,
-    fileExtension: '.png',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:pictures"],
-
-    test: TestRemove
-  },
-  {
-    type: 'videos',
-    shouldPass: true,
-    fileExtension: '.ogv',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestRemove
-  },
-  {
-    type: 'videos',
-    shouldPass: true,
-    fileExtension: '.ogg',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:videos"],
-
-    test: TestRemove
-  },
-  {
-    type: 'music',
-    shouldPass: true,
-    fileExtension: '.ogg',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestRemove
-  },
-  {
-    type: 'music',
-    shouldPass: false,
-    fileExtension: '.txt',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:music"],
-
-    test: TestRemove
-  },
-  {
-    type: 'sdcard',
-    shouldPass: true,
-    fileExtension: '.txt',
-
-    app: "https://example.com/manifest_cert.webapp",
-    permissions: ["device-storage:sdcard"],
-
-    test: TestRemove
-  }
-
 ];
 
 function setupTest(iframe,data) {
@@ -786,9 +556,6 @@ function runTest() {
     let data = gData.shift();
 
     iframe.setAttribute('mozbrowser', '');
-    if (data.app) {
-      iframe.setAttribute('mozapp', data.app);
-    }
 
     iframe.src = gTestUri;
 
diff --git a/dom/events/EventStateManager.cpp b/dom/events/EventStateManager.cpp
index 183e7ca07d63..c25127467e47 100644
--- a/dom/events/EventStateManager.cpp
+++ b/dom/events/EventStateManager.cpp
@@ -1260,9 +1260,9 @@ EventStateManager::IsRemoteTarget(nsIContent* target) {
     return true;
   }
 
-  // <frame/iframe mozbrowser/mozapp>
+  // <frame/iframe mozbrowser>
   nsCOMPtr<nsIMozBrowserFrame> browserFrame = do_QueryInterface(target);
-  if (browserFrame && browserFrame->GetReallyIsBrowserOrApp()) {
+  if (browserFrame && browserFrame->GetReallyIsBrowser()) {
     return !!TabParent::GetFrom(target);
   }
 
diff --git a/dom/html/nsBrowserElement.cpp b/dom/html/nsBrowserElement.cpp
index 858d1c7cb5b0..4b74ae969620 100644
--- a/dom/html/nsBrowserElement.cpp
+++ b/dom/html/nsBrowserElement.cpp
@@ -16,7 +16,6 @@
 
 #include "AudioChannelService.h"
 
-#include "mozIApplication.h"
 #include "nsComponentManagerUtils.h"
 #include "nsFrameLoader.h"
 #include "nsIAppsService.h"
@@ -43,13 +42,13 @@ nsBrowserElement::IsBrowserElementOrThrow(ErrorResult& aRv)
 void
 nsBrowserElement::InitBrowserElementAPI()
 {
-  bool isMozBrowserOrApp;
+  bool isMozBrowser;
   nsCOMPtr<nsIFrameLoader> frameLoader = GetFrameLoader();
   NS_ENSURE_TRUE_VOID(frameLoader);
-  nsresult rv = frameLoader->GetOwnerIsMozBrowserOrAppFrame(&isMozBrowserOrApp);
+  nsresult rv = frameLoader->GetOwnerIsMozBrowserFrame(&isMozBrowser);
   NS_ENSURE_SUCCESS_VOID(rv);
 
-  if (!isMozBrowserOrApp) {
+  if (!isMozBrowser) {
     return;
   }
 
@@ -494,13 +493,13 @@ nsBrowserElement::GetAllowedAudioChannels(
       return;
     }
 
-    bool isMozBrowserOrApp;
-    aRv = frameLoader->GetOwnerIsMozBrowserOrAppFrame(&isMozBrowserOrApp);
+    bool isMozBrowser;
+    aRv = frameLoader->GetOwnerIsMozBrowserFrame(&isMozBrowser);
     if (NS_WARN_IF(aRv.Failed())) {
       return;
     }
 
-    if (!isMozBrowserOrApp) {
+    if (!isMozBrowser) {
       return;
     }
 
diff --git a/dom/html/nsBrowserElement.h b/dom/html/nsBrowserElement.h
index e0f4ca186ff4..0217379dc3a3 100644
--- a/dom/html/nsBrowserElement.h
+++ b/dom/html/nsBrowserElement.h
@@ -124,7 +124,6 @@ public:
 
 protected:
   NS_IMETHOD_(already_AddRefed<nsFrameLoader>) GetFrameLoader() = 0;
-  NS_IMETHOD GetParentApplication(mozIApplication** aApplication) = 0;
 
   void InitBrowserElementAPI();
   void DestroyBrowserElementFrameScripts();
diff --git a/dom/html/nsGenericHTMLFrameElement.cpp b/dom/html/nsGenericHTMLFrameElement.cpp
index 6e50a40921df..76056536af4d 100644
--- a/dom/html/nsGenericHTMLFrameElement.cpp
+++ b/dom/html/nsGenericHTMLFrameElement.cpp
@@ -12,10 +12,8 @@
 #include "mozilla/Preferences.h"
 #include "mozilla/ErrorResult.h"
 #include "GeckoProfiler.h"
-#include "mozIApplication.h"
 #include "nsAttrValueInlines.h"
 #include "nsContentUtils.h"
-#include "nsIAppsService.h"
 #include "nsIDocShell.h"
 #include "nsIDOMDocument.h"
 #include "nsIFrame.h"
@@ -191,31 +189,6 @@ nsGenericHTMLFrameElement::GetFrameLoader()
   return loader.forget();
 }
 
-NS_IMETHODIMP
-nsGenericHTMLFrameElement::GetParentApplication(mozIApplication** aApplication)
-{
-  if (!aApplication) {
-    return NS_ERROR_FAILURE;
-  }
-
-  *aApplication = nullptr;
-
-  nsIPrincipal *principal = NodePrincipal();
-  uint32_t appId = principal->GetAppId();
-
-  nsCOMPtr<nsIAppsService> appsService = do_GetService(APPS_SERVICE_CONTRACTID);
-  if (NS_WARN_IF(!appsService)) {
-    return NS_ERROR_FAILURE;
-  }
-
-  nsresult rv = appsService->GetAppByLocalId(appId, aApplication);
-  if (NS_WARN_IF(NS_FAILED(rv))) {
-    return rv;
-  }
-
-  return NS_OK;
-}
-
 void
 nsGenericHTMLFrameElement::PresetOpenerWindow(mozIDOMWindowProxy* aWindow, ErrorResult& aRv)
 {
@@ -496,12 +469,12 @@ nsGenericHTMLFrameElement::BrowserFramesEnabled()
 }
 
 /**
- * Return true if this frame element really is a mozbrowser or mozapp.  (It
+ * Return true if this frame element really is a mozbrowser.  (It
  * needs to have the right attributes, and its creator must have the right
  * permissions.)
  */
 /* [infallible] */ nsresult
-nsGenericHTMLFrameElement::GetReallyIsBrowserOrApp(bool *aOut)
+nsGenericHTMLFrameElement::GetReallyIsBrowser(bool *aOut)
 {
   *aOut = false;
 
@@ -528,34 +501,6 @@ nsGenericHTMLFrameElement::GetReallyIsBrowserOrApp(bool *aOut)
   return NS_OK;
 }
 
-/* [infallible] */ NS_IMETHODIMP
-nsGenericHTMLFrameElement::GetReallyIsApp(bool *aOut)
-{
-  nsAutoString manifestURL;
-  GetAppManifestURL(manifestURL);
-
-  *aOut = !manifestURL.IsEmpty();
-  return NS_OK;
-}
-
-namespace {
-
-bool NestedEnabled()
-{
-  static bool sMozNestedEnabled = false;
-  static bool sBoolVarCacheInitialized = false;
-
-  if (!sBoolVarCacheInitialized) {
-    sBoolVarCacheInitialized = true;
-    Preferences::AddBoolVarCache(&sMozNestedEnabled,
-                                 "dom.ipc.tabs.nested.enabled");
-  }
-
-  return sMozNestedEnabled;
-}
-
-} // namespace
-
 /* [infallible] */ NS_IMETHODIMP
 nsGenericHTMLFrameElement::GetIsolated(bool *aOut)
 {
@@ -570,91 +515,6 @@ nsGenericHTMLFrameElement::GetIsolated(bool *aOut)
   return NS_OK;
 }
 
-/*
- * Get manifest url of app.
- */
-void nsGenericHTMLFrameElement::GetManifestURL(nsAString& aManifestURL)
-{
-  aManifestURL.Truncate();
-
-  nsAutoString manifestURL;
-  GetAttr(kNameSpaceID_None, nsGkAtoms::mozapp, manifestURL);
-  if (manifestURL.IsEmpty()) {
-    return;
-  }
-
-  // Check permission.
-  nsCOMPtr<nsIPermissionManager> permMgr = services::GetPermissionManager();
-  NS_ENSURE_TRUE_VOID(permMgr);
-  nsIPrincipal *principal = NodePrincipal();
-  const char* aPermissionType = "embed-apps";
-  uint32_t permission = nsIPermissionManager::DENY_ACTION;
-  nsresult rv = permMgr->TestPermissionFromPrincipal(principal,
-                                                     aPermissionType,
-                                                     &permission);
-  NS_ENSURE_SUCCESS_VOID(rv);
-  if (permission != nsIPermissionManager::ALLOW_ACTION) {
-    return;
-  }
-
-  nsCOMPtr<nsIAppsService> appsService = do_GetService(APPS_SERVICE_CONTRACTID);
-  NS_ENSURE_TRUE_VOID(appsService);
-
-  nsCOMPtr<mozIApplication> app;
-  appsService->GetAppByManifestURL(manifestURL, getter_AddRefs(app));
-
-  if (!app) {
-    return;
-  }
-
-  aManifestURL.Assign(manifestURL);
-}
-
-NS_IMETHODIMP
-nsGenericHTMLFrameElement::GetAppManifestURL(nsAString& aOut)
-{
-  aOut.Truncate();
-
-  // At the moment, you can't be an app without being a browser.
-  if (!nsIMozBrowserFrame::GetReallyIsBrowserOrApp()) {
-    return NS_OK;
-  }
-
-  // Only allow content process to embed an app when nested content
-  // process is enabled.
-  if (!XRE_IsParentProcess() &&
-      !(GetBoolAttr(nsGkAtoms::Remote) && NestedEnabled())){
-    NS_WARNING("Can't embed-apps. Embed-apps is restricted to in-proc apps "
-               "or content processes with nested pref enabled, see bug 1097479");
-    return NS_OK;
-  }
-
-  nsAutoString appManifestURL;
-
-  GetManifestURL(appManifestURL);
-
-  bool isApp = !appManifestURL.IsEmpty();
-
-  if (!isApp) {
-    // No valid case to get manifest
-    return NS_OK;
-  }
-
-  if (isApp) {
-    NS_WARNING("Can not simultaneously be mozapp");
-    return NS_OK;
-  }
-
-  nsAutoString manifestURL;
-  if (isApp) {
-    manifestURL.Assign(appManifestURL);
-  }
-
-  aOut.Assign(manifestURL);
-
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 nsGenericHTMLFrameElement::DisallowCreateFrameLoader()
 {
diff --git a/dom/indexedDB/test/file_app_isolation.html b/dom/indexedDB/test/file_app_isolation.html
deleted file mode 100644
index 0ff74e68979e..000000000000
--- a/dom/indexedDB/test/file_app_isolation.html
+++ /dev/null
@@ -1,88 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <body>
-    foobar!
-  </body>
-  <script>
-    var data = [
-      { id: "0", name: "foo" },
-    ];
-
-    var action = window.location.search.substring(1);
-    var finished = false;
-    var created = false; // We use that for 'read-no' action.
-
-    function finish(value) {
-      value ? alert('success') : alert('failure');
-      finished = true;
-    }
-
-    var request = window.indexedDB.open('AppIsolationTest');
-
-    request.onupgradeneeded = function(event) {
-      if (finished) {
-        finish(false);
-        return;
-      }
-
-      switch (action) {
-        case 'read-no':
-          created = true;
-          break;
-        case 'read-yes':
-          finish(false);
-          break;
-        case 'write':
-          created = true;
-
-          var db = event.target.result;
-
-          var objectStore = db.createObjectStore("test", { keyPath: "id" });
-          for (var i in data) {
-            objectStore.add(data[i]);
-          }
-          break;
-      }
-    }
-
-    request.onsuccess = function(event) {
-      if (finished) {
-        finish(false);
-        return;
-      }
-
-      var db = event.target.result;
-
-      // Think about close the db!
-      switch (action) {
-        case 'read-no':
-          db.close();
-
-          if (created) { // That means we have created it.
-            indexedDB.deleteDatabase('AppIsolationTest').onsuccess = function() {
-              finish(true);
-            };
-          } else {
-            finish(false);
-          }
-          break;
-        case 'read-yes':
-          db.transaction("test").objectStore("test").get("0").onsuccess = function(event) {
-            var name = event.target.result.name;
-            db.close();
-
-            indexedDB.deleteDatabase('AppIsolationTest').onsuccess = function() {
-              finish(name == 'foo');
-            };
-          };
-          break;
-        case 'write':
-          db.close();
-
-          // Success only if the db was actually created.
-          finish(created);
-          break;
-      }
-    };
-  </script>
-</html>
diff --git a/dom/indexedDB/test/file_app_isolation.js b/dom/indexedDB/test/file_app_isolation.js
deleted file mode 100644
index d6ed3fab4419..000000000000
--- a/dom/indexedDB/test/file_app_isolation.js
+++ /dev/null
@@ -1,161 +0,0 @@
-SimpleTest.waitForExplicitFinish();
-
-var fileTestOnCurrentOrigin = (location.protocol + '//' + location.host + location.pathname)
-                              .replace('test_', 'file_')
-                              .replace('_inproc', '').replace('_oop', '');
-
-var previousPrefs = {
-  mozBrowserFramesEnabled: undefined,
-  oop_by_default: undefined,
-};
-
-try {
-  previousPrefs.mozBrowserFramesEnabled = SpecialPowers.getBoolPref('dom.mozBrowserFramesEnabled');
-} catch(e)
-{
-}
-
-try {
-  previousPrefs.oop_by_default = SpecialPowers.getBoolPref('dom.ipc.browser_frames.oop_by_default');
-} catch(e) {
-}
-
-SpecialPowers.setBoolPref('dom.mozBrowserFramesEnabled', true);
-SpecialPowers.setBoolPref("dom.ipc.browser_frames.oop_by_default", location.pathname.indexOf('_inproc') == -1);
-
-SpecialPowers.addPermission("browser", true, window.document);
-
-var gData = [
-  // APP 1
-  {
-    app: 'http://example.org/manifest.webapp',
-    action: 'read-no',
-    src: fileTestOnCurrentOrigin,
-  },
-  {
-    app: 'http://example.org/manifest.webapp',
-    action: 'write',
-    src: fileTestOnCurrentOrigin,
-  },
-  {
-    app: 'http://example.org/manifest.webapp',
-    action: 'read-yes',
-    src: fileTestOnCurrentOrigin,
-  },
-  // APP 2
-  {
-    app: 'https://example.com/manifest.webapp',
-    action: 'read-no',
-    src: fileTestOnCurrentOrigin,
-  },
-  {
-    app: 'https://example.com/manifest.webapp',
-    action: 'write',
-    src: fileTestOnCurrentOrigin,
-  },
-  {
-    app: 'https://example.com/manifest.webapp',
-    action: 'read-yes',
-    src: fileTestOnCurrentOrigin,
-  },
-  // Browser
-  {
-    browser: true,
-    action: 'read-no',
-    src: fileTestOnCurrentOrigin,
-  },
-  {
-    browser: true,
-    action: 'write',
-    src: fileTestOnCurrentOrigin,
-  },
-  {
-    browser: true,
-    action: 'read-yes',
-    src: fileTestOnCurrentOrigin,
-  },
-];
-
-function runTest() {
-  for (var i in gData) {
-    var iframe = document.createElement('iframe');
-    var data = gData[i];
-
-    if (data.app) {
-      iframe.setAttribute('mozbrowser', '');
-      iframe.setAttribute('mozapp', data.app);
-    } else if (data.browser) {
-      iframe.setAttribute('mozbrowser', '');
-    }
-
-    if (data.app || data.browser) {
-      iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
-        is(e.detail.message, 'success', 'test number ' + i);
-
-//        document.getElementById('content').removeChild(iframe);
-
-        i++;
-        if (i >= gData.length) {
-          if (previousPrefs.mozBrowserFramesEnabled !== undefined) {
-            SpecialPowers.setBoolPref('dom.mozBrowserFramesEnabled', previousPrefs.mozBrowserFramesEnabled);
-          }
-          if (previousPrefs.oop_by_default !== undefined) {
-            SpecialPowers.setBoolPref("dom.ipc.browser_frames.oop_by_default", previousPrefs.oop_by_default);
-          }
-
-          SpecialPowers.removePermission("browser", window.document);
-
-          indexedDB.deleteDatabase('AppIsolationTest').onsuccess = function() {
-            SimpleTest.finish();
-          };
-        } else {
-          gTestRunner.next();
-        }
-      });
-    }
-
-    iframe.src = data.src + '?' + data.action;
-
-    document.getElementById('content').appendChild(iframe);
-
-    yield undefined;
-  }
-}
-
-var gTestRunner = runTest();
-
-function startTest() {
-  var request = window.indexedDB.open('AppIsolationTest');
-  var created = false;
-
-  request.onupgradeneeded = function(event) {
-    created = true;
-    var db = event.target.result;
-    var data = [
-      { id: "0", name: "foo" },
-    ];
-    var objectStore = db.createObjectStore("test", { keyPath: "id" });
-    for (var i in data) {
-      objectStore.add(data[i]);
-    }
-  }
-
-  request.onsuccess = function(event) {
-    var db = event.target.result;
-    is(created, true, "we should have created the db");
-
-    db.transaction("test").objectStore("test").get("0").onsuccess = function(event) {
-      is(event.target.result.name, 'foo', 'data have been written');
-      db.close();
-
-      gTestRunner.next();
-    };
-  }
-}
-
-// TODO: remove unsetting network.disable.ipc.security as part of bug 820712
-SpecialPowers.pushPrefEnv({
-  "set": [
-    ["network.disable.ipc.security", true],
-  ]
-}, startTest);
diff --git a/dom/indexedDB/test/mochitest.ini b/dom/indexedDB/test/mochitest.ini
index 8826702ae638..a91041173704 100644
--- a/dom/indexedDB/test/mochitest.ini
+++ b/dom/indexedDB/test/mochitest.ini
@@ -11,8 +11,6 @@ support-files =
   event_propagation_iframe.html
   exceptions_in_events_iframe.html
   file.js
-  file_app_isolation.html
-  file_app_isolation.js
   helpers.js
   leaving_page_iframe.html
   service_worker.js
@@ -123,12 +121,6 @@ support-files =
 [test_add_put.html]
 [test_add_twice_failure.html]
 [test_advance.html]
-[test_app_isolation_inproc.html]
-# The app isolation tests are only supposed to run in the main process.
-skip-if = e10s
-[test_app_isolation_oop.html]
-# The app isolation tests are only supposed to run in the main process.
-skip-if = e10s
 [test_autoIncrement.html]
 [test_autoIncrement_indexes.html]
 [test_bfcache.html]
diff --git a/dom/indexedDB/test/test_app_isolation_inproc.html b/dom/indexedDB/test/test_app_isolation_inproc.html
deleted file mode 100644
index 571189877f8b..000000000000
--- a/dom/indexedDB/test/test_app_isolation_inproc.html
+++ /dev/null
@@ -1,21 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=756645
--->
-<head>
-  <title>Test for IndexedDB app isolation (unique process)</title>
-  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
-</head>
-<body>
-<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=756645">Mozilla Bug 756645</a>
-<div id="content" style="display: none">
-  
-</div>
-<pre id="test">
-<script type="application/javascript;version=1.7" src="file_app_isolation.js">
-</script>
-</pre>
-</body>
-</html>
diff --git a/dom/indexedDB/test/test_app_isolation_oop.html b/dom/indexedDB/test/test_app_isolation_oop.html
deleted file mode 100644
index 571189877f8b..000000000000
--- a/dom/indexedDB/test/test_app_isolation_oop.html
+++ /dev/null
@@ -1,21 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=756645
--->
-<head>
-  <title>Test for IndexedDB app isolation (unique process)</title>
-  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
-</head>
-<body>
-<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=756645">Mozilla Bug 756645</a>
-<div id="content" style="display: none">
-  
-</div>
-<pre id="test">
-<script type="application/javascript;version=1.7" src="file_app_isolation.js">
-</script>
-</pre>
-</body>
-</html>
diff --git a/dom/inputmethod/Keyboard.jsm b/dom/inputmethod/Keyboard.jsm
index 22f87ffbcfc6..cb21103973b1 100644
--- a/dom/inputmethod/Keyboard.jsm
+++ b/dom/inputmethod/Keyboard.jsm
@@ -190,8 +190,8 @@ this.Keyboard = {
         this.formMM = null;
       }
     } else {
-      // Ignore notifications that aren't from a BrowserOrApp
-      if (!frameLoader.ownerIsMozBrowserOrAppFrame) {
+      // Ignore notifications that aren't from a Browser
+      if (!frameLoader.ownerIsMozBrowserFrame) {
         return;
       }
       this.initFormsFrameScript(mm);
diff --git a/dom/interfaces/html/nsIMozBrowserFrame.idl b/dom/interfaces/html/nsIMozBrowserFrame.idl
index a9dccdd1ceea..fa5fdb6240ae 100644
--- a/dom/interfaces/html/nsIMozBrowserFrame.idl
+++ b/dom/interfaces/html/nsIMozBrowserFrame.idl
@@ -13,22 +13,13 @@ interface nsITabParent;
 interface nsIMozBrowserFrame : nsIDOMMozBrowserFrame
 {
   /**
-   * Gets whether this frame really is a browser or app frame.
+   * Gets whether this frame really is a browser frame.
    *
    * In order to really be a browser frame, this frame's
    * nsIDOMMozBrowserFrame::mozbrowser attribute must be true, and the frame
    * may have to pass various security checks.
    */
-  [infallible] readonly attribute boolean reallyIsBrowserOrApp;
-
-  /**
-   * Gets whether this frame really is an app frame.
-   *
-   * In order to really be an app frame, this frame must really be a browser
-   * frame (this requirement will go away eventually), and  the frame's mozapp
-   * attribute must point to the manifest of a valid app.
-   */
-  [infallible] readonly attribute boolean reallyIsApp;
+  [infallible] readonly attribute boolean reallyIsBrowser;
 
   /**
    * Gets whether this frame is an isolated frame.
@@ -44,14 +35,6 @@ interface nsIMozBrowserFrame : nsIDOMMozBrowserFrame
    */
   [infallible] readonly attribute boolean isolated;
 
-  /**
-   * Gets this frame's app manifest URL, if the frame really is an app frame.
-   * Otherwise, returns the empty string.
-   *
-   * This method is guaranteed not to fail.
-   */
-  readonly attribute AString appManifestURL;
-
   /**
    * Normally, a frame tries to create its frame loader when its src is
    * modified, or its contentWindow is accessed.
diff --git a/dom/ipc/ContentBridgeChild.cpp b/dom/ipc/ContentBridgeChild.cpp
index 8f6f4a3a8e64..3ba58a382ee3 100644
--- a/dom/ipc/ContentBridgeChild.cpp
+++ b/dom/ipc/ContentBridgeChild.cpp
@@ -78,7 +78,6 @@ ContentBridgeChild::SendPBrowserConstructor(PBrowserChild* aActor,
                                             const IPCTabContext& aContext,
                                             const uint32_t& aChromeFlags,
                                             const ContentParentId& aCpID,
-                                            const bool& aIsForApp,
                                             const bool& aIsForBrowser)
 {
   return PContentBridgeChild::SendPBrowserConstructor(aActor,
@@ -86,7 +85,6 @@ ContentBridgeChild::SendPBrowserConstructor(PBrowserChild* aActor,
                                                       aContext,
                                                       aChromeFlags,
                                                       aCpID,
-                                                      aIsForApp,
                                                       aIsForBrowser);
 }
 
@@ -131,14 +129,12 @@ ContentBridgeChild::AllocPBrowserChild(const TabId& aTabId,
                                        const IPCTabContext &aContext,
                                        const uint32_t& aChromeFlags,
                                        const ContentParentId& aCpID,
-                                       const bool& aIsForApp,
                                        const bool& aIsForBrowser)
 {
   return nsIContentChild::AllocPBrowserChild(aTabId,
                                              aContext,
                                              aChromeFlags,
                                              aCpID,
-                                             aIsForApp,
                                              aIsForBrowser);
 }
 
@@ -154,7 +150,6 @@ ContentBridgeChild::RecvPBrowserConstructor(PBrowserChild* aActor,
                                             const IPCTabContext& aContext,
                                             const uint32_t& aChromeFlags,
                                             const ContentParentId& aCpID,
-                                            const bool& aIsForApp,
                                             const bool& aIsForBrowser)
 {
   if (!ContentChild::GetSingleton()->RecvPBrowserConstructor(aActor,
@@ -162,7 +157,6 @@ ContentBridgeChild::RecvPBrowserConstructor(PBrowserChild* aActor,
                                                              aContext,
                                                              aChromeFlags,
                                                              aCpID,
-                                                             aIsForApp,
                                                              aIsForBrowser)) {
     return IPC_FAIL_NO_REASON(this);
   }
diff --git a/dom/ipc/ContentBridgeChild.h b/dom/ipc/ContentBridgeChild.h
index 9ff4c0521074..04cccc0ca602 100644
--- a/dom/ipc/ContentBridgeChild.h
+++ b/dom/ipc/ContentBridgeChild.h
@@ -43,7 +43,6 @@ public:
                                        const IPCTabContext& aContext,
                                        const uint32_t& aChromeFlags,
                                        const ContentParentId& aCpID,
-                                       const bool& aIsForApp,
                                        const bool& aIsForBrowser) override;
 
   virtual mozilla::ipc::PFileDescriptorSetChild*
@@ -61,7 +60,6 @@ protected:
                                             const IPCTabContext& aContext,
                                             const uint32_t& aChromeFlags,
                                             const ContentParentId& aCpID,
-                                            const bool& aIsForApp,
                                             const bool& aIsForBrowser) override;
   virtual bool DeallocPBrowserChild(PBrowserChild*) override;
   virtual mozilla::ipc::IPCResult RecvPBrowserConstructor(PBrowserChild* aCctor,
@@ -69,7 +67,6 @@ protected:
                                                           const IPCTabContext& aContext,
                                                           const uint32_t& aChromeFlags,
                                                           const ContentParentId& aCpID,
-                                                          const bool& aIsForApp,
                                                           const bool& aIsForBrowser) override;
 
   virtual mozilla::jsipc::PJavaScriptChild* AllocPJavaScriptChild() override;
diff --git a/dom/ipc/ContentBridgeParent.cpp b/dom/ipc/ContentBridgeParent.cpp
index be36da79a3d7..872238335dc1 100644
--- a/dom/ipc/ContentBridgeParent.cpp
+++ b/dom/ipc/ContentBridgeParent.cpp
@@ -103,7 +103,6 @@ ContentBridgeParent::SendPBrowserConstructor(PBrowserParent* aActor,
                                              const IPCTabContext& aContext,
                                              const uint32_t& aChromeFlags,
                                              const ContentParentId& aCpID,
-                                             const bool& aIsForApp,
                                              const bool& aIsForBrowser)
 {
   return PContentBridgeParent::SendPBrowserConstructor(aActor,
@@ -111,7 +110,6 @@ ContentBridgeParent::SendPBrowserConstructor(PBrowserParent* aActor,
                                                        aContext,
                                                        aChromeFlags,
                                                        aCpID,
-                                                       aIsForApp,
                                                        aIsForBrowser);
 }
 
@@ -144,14 +142,12 @@ ContentBridgeParent::AllocPBrowserParent(const TabId& aTabId,
                                          const IPCTabContext &aContext,
                                          const uint32_t& aChromeFlags,
                                          const ContentParentId& aCpID,
-                                         const bool& aIsForApp,
                                          const bool& aIsForBrowser)
 {
   return nsIContentParent::AllocPBrowserParent(aTabId,
                                                aContext,
                                                aChromeFlags,
                                                aCpID,
-                                               aIsForApp,
                                                aIsForBrowser);
 }
 
diff --git a/dom/ipc/ContentBridgeParent.h b/dom/ipc/ContentBridgeParent.h
index d4a69e2c880d..d377538335d6 100644
--- a/dom/ipc/ContentBridgeParent.h
+++ b/dom/ipc/ContentBridgeParent.h
@@ -43,7 +43,6 @@ public:
                           const IPCTabContext& aContext,
                           const uint32_t& aChromeFlags,
                           const ContentParentId& aCpID,
-                          const bool& aIsForApp,
                           const bool& aIsForBrowser) override;
 
   FORWARD_SHMEM_ALLOCATOR_TO(PContentBridgeParent)
@@ -54,10 +53,6 @@ public:
   {
     return mChildID;
   }
-  virtual bool IsForApp() const override
-  {
-    return mIsForApp;
-  }
   virtual bool IsForBrowser() const override
   {
     return mIsForBrowser;
@@ -76,11 +71,6 @@ protected:
     mChildID = aId;
   }
 
-  void SetIsForApp(bool aIsForApp)
-  {
-    mIsForApp = aIsForApp;
-  }
-
   void SetIsForBrowser(bool aIsForBrowser)
   {
     mIsForBrowser = aIsForBrowser;
@@ -115,7 +105,6 @@ protected:
                       const IPCTabContext &aContext,
                       const uint32_t& aChromeFlags,
                       const ContentParentId& aCpID,
-                      const bool& aIsForApp,
                       const bool& aIsForBrowser) override;
 
   virtual bool DeallocPBrowserParent(PBrowserParent*) override;
@@ -141,7 +130,6 @@ protected: // members
   RefPtr<ContentBridgeParent> mSelfRef;
   Transport* mTransport; // owned
   ContentParentId mChildID;
-  bool mIsForApp;
   bool mIsForBrowser;
 
 private:
diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index 07adfd4dc068..98f66ef40bc1 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -591,7 +591,7 @@ ContentChild::Init(MessageLoop* aIOLoop,
                                 XRE_GetProcessType());
 #endif
 
-  SendGetProcessAttributes(&mID, &mIsForApp, &mIsForBrowser);
+  SendGetProcessAttributes(&mID, &mIsForBrowser);
   InitProcessAttributes();
 
 #ifdef NS_PRINTING
@@ -607,10 +607,10 @@ void
 ContentChild::InitProcessAttributes()
 {
 #ifdef MOZ_WIDGET_GONK
-  if (mIsForApp && !mIsForBrowser) {
-    SetProcessName(NS_LITERAL_STRING("(Preallocated app)"), false);
-  } else {
+  if (mIsForBrowser) {
     SetProcessName(NS_LITERAL_STRING("Browser"), false);
+  } else {
+    SetProcessName(NS_LITERAL_STRING("(Preallocated app)"), false);
   }
 #else
   SetProcessName(NS_LITERAL_STRING("Web Content"), true);
@@ -723,7 +723,7 @@ ContentChild::ProvideWindowCommon(TabChild* aTabOpener,
     // We release this ref in DeallocPBrowserChild
     RefPtr<TabChild>(newChild).forget().take(),
     tabId, *ipcContext, aChromeFlags,
-    GetID(), IsForApp(), IsForBrowser());
+    GetID(), IsForBrowser());
 
   nsString name(aName);
   nsAutoCString features(aFeatures);
@@ -1518,14 +1518,12 @@ ContentChild::AllocPBrowserChild(const TabId& aTabId,
                                  const IPCTabContext& aContext,
                                  const uint32_t& aChromeFlags,
                                  const ContentParentId& aCpID,
-                                 const bool& aIsForApp,
                                  const bool& aIsForBrowser)
 {
   return nsIContentChild::AllocPBrowserChild(aTabId,
                                              aContext,
                                              aChromeFlags,
                                              aCpID,
-                                             aIsForApp,
                                              aIsForBrowser);
 }
 
@@ -1535,7 +1533,6 @@ ContentChild::SendPBrowserConstructor(PBrowserChild* aActor,
                                       const IPCTabContext& aContext,
                                       const uint32_t& aChromeFlags,
                                       const ContentParentId& aCpID,
-                                      const bool& aIsForApp,
                                       const bool& aIsForBrowser)
 {
   return PContentChild::SendPBrowserConstructor(aActor,
@@ -1543,7 +1540,6 @@ ContentChild::SendPBrowserConstructor(PBrowserChild* aActor,
                                                 aContext,
                                                 aChromeFlags,
                                                 aCpID,
-                                                aIsForApp,
                                                 aIsForBrowser);
 }
 
@@ -1553,7 +1549,6 @@ ContentChild::RecvPBrowserConstructor(PBrowserChild* aActor,
                                       const IPCTabContext& aContext,
                                       const uint32_t& aChromeFlags,
                                       const ContentParentId& aCpID,
-                                      const bool& aIsForApp,
                                       const bool& aIsForBrowser)
 {
   // This runs after AllocPBrowserChild() returns and the IPC machinery for this
@@ -1578,7 +1573,6 @@ ContentChild::RecvPBrowserConstructor(PBrowserChild* aActor,
     // Redo InitProcessAttributes() when the app or browser is really
     // launching so the attributes will be correct.
     mID = aCpID;
-    mIsForApp = aIsForApp;
     mIsForBrowser = aIsForBrowser;
     InitProcessAttributes();
   }
@@ -2438,7 +2432,7 @@ ContentChild::RecvAppInit()
   // PreloadSlowThings() may set the docshell of the first TabChild
   // inactive, and we can only safely restore it to active from
   // BrowserElementChild.js.
-  if (mIsForApp || mIsForBrowser) {
+  if (mIsForBrowser) {
     PreloadSlowThings();
   }
 
diff --git a/dom/ipc/ContentChild.h b/dom/ipc/ContentChild.h
index cbfb2bc45735..ec6ca83a81e0 100644
--- a/dom/ipc/ContentChild.h
+++ b/dom/ipc/ContentChild.h
@@ -193,7 +193,6 @@ public:
                                             const IPCTabContext& aContext,
                                             const uint32_t& aChromeFlags,
                                             const ContentParentId& aCpID,
-                                            const bool& aIsForApp,
                                             const bool& aIsForBrowser) override;
 
   virtual bool DeallocPBrowserChild(PBrowserChild*) override;
@@ -542,7 +541,6 @@ public:
   uint32_t GetMsaaID() const { return mMsaaID; }
 #endif
 
-  bool IsForApp() const { return mIsForApp; }
   bool IsForBrowser() const { return mIsForBrowser; }
 
   virtual PBlobChild*
@@ -563,7 +561,6 @@ public:
                                        const IPCTabContext& context,
                                        const uint32_t& chromeFlags,
                                        const ContentParentId& aCpID,
-                                       const bool& aIsForApp,
                                        const bool& aIsForBrowser) override;
 
   virtual mozilla::ipc::IPCResult RecvPBrowserConstructor(PBrowserChild* aCctor,
@@ -571,7 +568,6 @@ public:
                                                           const IPCTabContext& aContext,
                                                           const uint32_t& aChromeFlags,
                                                           const ContentParentId& aCpID,
-                                                          const bool& aIsForApp,
                                                           const bool& aIsForBrowser) override;
 
   FORWARD_SHMEM_ALLOCATOR_TO(PContentChild)
@@ -677,7 +673,6 @@ private:
 
   AppInfo mAppInfo;
 
-  bool mIsForApp;
   bool mIsForBrowser;
   bool mCanOverrideProcessName;
   bool mIsAlive;
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index 0b5445cb686c..2c3cd2f41023 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -33,7 +33,6 @@
 #include "HandlerServiceParent.h"
 #include "IHistory.h"
 #include "imgIContainer.h"
-#include "mozIApplication.h"
 #if defined(XP_WIN) && defined(ACCESSIBILITY)
 #include "mozilla/a11y/AccessibleWrap.h"
 #include "mozilla/WindowsVersion.h"
@@ -505,8 +504,7 @@ ContentParentsMemoryReporter::CollectReports(
   return NS_OK;
 }
 
-nsDataHashtable<nsStringHashKey, ContentParent*>* ContentParent::sAppContentParents;
-nsTArray<ContentParent*>* ContentParent::sNonAppContentParents;
+nsTArray<ContentParent*>* ContentParent::sBrowserContentParents;
 nsTArray<ContentParent*>* ContentParent::sLargeAllocationContentParents;
 nsTArray<ContentParent*>* ContentParent::sPrivateContent;
 StaticAutoPtr<LinkedList<ContentParent> > ContentParent::sContentParents;
@@ -525,11 +523,6 @@ static bool sDisableUnsafeCPOWWarnings = false;
 // The first content child has ID 1, so the chrome process can have ID 0.
 static uint64_t gContentChildID = 1;
 
-// We want the prelaunched process to know that it's for apps, but not
-// actually for any app in particular.  Use a magic manifest URL.
-// Can't be a static constant.
-#define MAGIC_PREALLOCATED_APP_MANIFEST_URL NS_LITERAL_STRING("{{template}}")
-
 static const char* sObserverTopics[] = {
   "xpcom-shutdown",
   "profile-before-change",
@@ -567,8 +560,7 @@ static const char* sObserverTopics[] = {
 ContentParent::PreallocateAppProcess()
 {
   RefPtr<ContentParent> process =
-    new ContentParent(/* app = */ nullptr,
-                      /* aOpener = */ nullptr,
+    new ContentParent(/* aOpener = */ nullptr,
                       /* isForBrowserElement = */ false,
                       /* isForPreallocated = */ true);
 
@@ -580,57 +572,6 @@ ContentParent::PreallocateAppProcess()
   return process.forget();
 }
 
-/*static*/ already_AddRefed<ContentParent>
-ContentParent::GetNewOrPreallocatedAppProcess(mozIApplication* aApp,
-                                              ProcessPriority aInitialPriority,
-                                              ContentParent* aOpener,
-                                              /*out*/ bool* aTookPreAllocated)
-{
-  MOZ_ASSERT(aApp);
-  RefPtr<ContentParent> process = PreallocatedProcessManager::Take();
-
-  if (process) {
-    if (!process->SetPriorityAndCheckIsAlive(aInitialPriority)) {
-      // Kill the process just in case it's not actually dead; we don't want
-      // to "leak" this process!
-      process->KillHard("GetNewOrPreallocatedAppProcess");
-    }
-    else {
-      nsAutoString manifestURL;
-      if (NS_FAILED(aApp->GetManifestURL(manifestURL))) {
-        NS_ERROR("Failed to get manifest URL");
-        return nullptr;
-      }
-      process->TransformPreallocatedIntoApp(aOpener, manifestURL);
-      process->ForwardKnownInfo();
-
-      if (aTookPreAllocated) {
-        *aTookPreAllocated = true;
-      }
-      return process.forget();
-    }
-  }
-
-  NS_WARNING("Unable to use pre-allocated app process");
-  process = new ContentParent(aApp,
-                              /* aOpener = */ aOpener,
-                              /* isForBrowserElement = */ false,
-                              /* isForPreallocated = */ false);
-
-  if (!process->LaunchSubprocess(aInitialPriority)) {
-    return nullptr;
-  }
-
-  process->Init();
-  process->ForwardKnownInfo();
-
-  if (aTookPreAllocated) {
-    *aTookPreAllocated = false;
-  }
-
-  return process.forget();
-}
-
 /*static*/ void
 ContentParent::StartUp()
 {
@@ -752,10 +693,10 @@ ContentParent::GetNewOrUsedBrowserProcess(bool aForBrowserElement,
 
     maxContentParents = Preferences::GetInt("dom.ipc.dedicatedProcessCount", 2);
   } else {
-    if (!sNonAppContentParents) {
-      sNonAppContentParents = new nsTArray<ContentParent*>();
+    if (!sBrowserContentParents) {
+      sBrowserContentParents = new nsTArray<ContentParent*>();
     }
-    contentParents = sNonAppContentParents;
+    contentParents = sBrowserContentParents;
 
     maxContentParents = Preferences::GetInt("dom.ipc.processCount", 1);
   }
@@ -771,7 +712,7 @@ ContentParent::GetNewOrUsedBrowserProcess(bool aForBrowserElement,
     uint32_t currIdx = startIdx;
     do {
       RefPtr<ContentParent> p = (*contentParents)[currIdx];
-      NS_ASSERTION(p->IsAlive(), "Non-alive contentparent in sNonAppContntParents?");
+      NS_ASSERTION(p->IsAlive(), "Non-alive contentparent in sBrowserContentParents?");
       if (p->mOpener == aOpener) {
         return p.forget();
       }
@@ -785,8 +726,7 @@ ContentParent::GetNewOrUsedBrowserProcess(bool aForBrowserElement,
     p->TransformPreallocatedIntoBrowser(aOpener);
   } else {
     // Failed in using the preallocated process: fork from the chrome process.
-    p = new ContentParent(/* app = */ nullptr,
-                          aOpener,
+    p = new ContentParent(aOpener,
                           aForBrowserElement,
                           /* isForPreallocated = */ false);
 
@@ -862,7 +802,6 @@ ContentParent::RecvCreateChildProcess(const IPCTabContext& aContext,
                                       const hal::ProcessPriority& aPriority,
                                       const TabId& aOpenerTabId,
                                       ContentParentId* aCpId,
-                                      bool* aIsForApp,
                                       bool* aIsForBrowser,
                                       TabId* aTabId)
 {
@@ -880,24 +819,16 @@ ContentParent::RecvCreateChildProcess(const IPCTabContext& aContext,
     return IPC_FAIL_NO_REASON(this);
   }
 
-  nsCOMPtr<mozIApplication> ownApp = tc.GetTabContext().GetOwnApp();
-  if (ownApp) {
-    cp = GetNewOrPreallocatedAppProcess(ownApp, aPriority, this);
-  }
-  else {
-   cp = GetNewOrUsedBrowserProcess(/* isBrowserElement = */ true,
-                                   aPriority, this);
-  }
+  cp = GetNewOrUsedBrowserProcess(/* isBrowserElement = */ true,
+                                  aPriority, this);
 
   if (!cp) {
     *aCpId = 0;
-    *aIsForApp = false;
     *aIsForBrowser = false;
     return IPC_OK();
   }
 
   *aCpId = cp->ChildID();
-  *aIsForApp = cp->IsForApp();
   *aIsForBrowser = cp->IsForBrowser();
 
   ContentProcessManager *cpm = ContentProcessManager::GetSingleton();
@@ -1046,10 +977,10 @@ ContentParent::RecvFindPlugins(const uint32_t& aPluginEpoch,
 }
 
 /*static*/ TabParent*
-ContentParent::CreateBrowserOrApp(const TabContext& aContext,
-                                  Element* aFrameElement,
-                                  ContentParent* aOpenerContentParent,
-                                  bool aFreshProcess)
+ContentParent::CreateBrowser(const TabContext& aContext,
+                             Element* aFrameElement,
+                             ContentParent* aOpenerContentParent,
+                             bool aFreshProcess)
 {
   PROFILER_LABEL_FUNC(js::ProfileEntry::Category::OTHER);
 
@@ -1072,222 +1003,75 @@ ContentParent::CreateBrowserOrApp(const TabContext& aContext,
     openerTabId = TabParent::GetTabIdFrom(docShell);
   }
 
-  if (aContext.IsMozBrowserElement() || !aContext.HasOwnApp()) {
-    RefPtr<nsIContentParent> constructorSender;
-    if (isInContentProcess) {
-      MOZ_ASSERT(aContext.IsMozBrowserElement());
-      constructorSender = CreateContentBridgeParent(aContext, initialPriority,
-                                                    openerTabId, &tabId);
-    } else {
-      if (aOpenerContentParent) {
-        constructorSender = aOpenerContentParent;
-      } else {
-        constructorSender =
-          GetNewOrUsedBrowserProcess(aContext.IsMozBrowserElement(),
-                                     initialPriority,
-                                     nullptr,
-                                     aFreshProcess);
-        if (!constructorSender) {
-          return nullptr;
-        }
-      }
-      tabId = AllocateTabId(openerTabId,
-                            aContext.AsIPCTabContext(),
-                            constructorSender->ChildID());
-    }
-    if (constructorSender) {
-      nsCOMPtr<nsIDocShellTreeOwner> treeOwner;
-      docShell->GetTreeOwner(getter_AddRefs(treeOwner));
-      if (!treeOwner) {
-        return nullptr;
-      }
-
-      nsCOMPtr<nsIWebBrowserChrome> wbc = do_GetInterface(treeOwner);
-      if (!wbc) {
-        return nullptr;
-      }
-      uint32_t chromeFlags = 0;
-      wbc->GetChromeFlags(&chromeFlags);
-
-      nsCOMPtr<nsILoadContext> loadContext = do_QueryInterface(docShell);
-      if (loadContext && loadContext->UsePrivateBrowsing()) {
-        chromeFlags |= nsIWebBrowserChrome::CHROME_PRIVATE_WINDOW;
-      }
-      if (docShell->GetAffectPrivateSessionLifetime()) {
-        chromeFlags |= nsIWebBrowserChrome::CHROME_PRIVATE_LIFETIME;
-      }
-
-      if (tabId == 0) {
-        return nullptr;
-      }
-      RefPtr<TabParent> tp(new TabParent(constructorSender, tabId,
-                                         aContext, chromeFlags));
-      tp->SetInitedByParent();
-
-      PBrowserParent* browser =
-      constructorSender->SendPBrowserConstructor(
-        // DeallocPBrowserParent() releases this ref.
-        tp.forget().take(), tabId,
-        aContext.AsIPCTabContext(),
-        chromeFlags,
-        constructorSender->ChildID(),
-        constructorSender->IsForApp(),
-        constructorSender->IsForBrowser());
-
-      if (aFreshProcess) {
-        Unused << browser->SendSetFreshProcess();
-      }
-
-      if (browser) {
-        RefPtr<TabParent> constructedTabParent = TabParent::GetFrom(browser);
-        constructedTabParent->SetOwnerElement(aFrameElement);
-        return constructedTabParent;
-      }
-    }
-    return nullptr;
-  }
-
-  // If we got here, we have an app and we're not a browser element.  ownApp
-  // shouldn't be null, because we otherwise would have gone into the
-  // !HasOwnApp() branch above.
-  RefPtr<nsIContentParent> parent;
-  bool reused = false;
-  bool tookPreallocated = false;
-  nsAutoString manifestURL;
-
+  RefPtr<nsIContentParent> constructorSender;
   if (isInContentProcess) {
-    parent = CreateContentBridgeParent(aContext,
-                                       initialPriority,
-                                       openerTabId,
-                                       &tabId);
-  }
-  else {
-    nsCOMPtr<mozIApplication> ownApp = aContext.GetOwnApp();
-
-    if (!sAppContentParents) {
-      sAppContentParents =
-        new nsDataHashtable<nsStringHashKey, ContentParent*>();
+    MOZ_ASSERT(aContext.IsMozBrowserElement());
+    constructorSender = CreateContentBridgeParent(aContext, initialPriority,
+                                                  openerTabId, &tabId);
+  } else {
+    if (aOpenerContentParent) {
+      constructorSender = aOpenerContentParent;
+    } else {
+      constructorSender =
+        GetNewOrUsedBrowserProcess(aContext.IsMozBrowserElement(),
+                                   initialPriority, nullptr, aFreshProcess);
+      if (!constructorSender) {
+        return nullptr;
+      }
     }
-
-    // Each app gets its own ContentParent instance unless it shares it with
-    // a parent app.
-    if (NS_FAILED(ownApp->GetManifestURL(manifestURL))) {
-      NS_ERROR("Failed to get manifest URL");
+    tabId = AllocateTabId(openerTabId,
+                          aContext.AsIPCTabContext(),
+                          constructorSender->ChildID());
+  }
+  if (constructorSender) {
+    nsCOMPtr<nsIDocShellTreeOwner> treeOwner;
+    docShell->GetTreeOwner(getter_AddRefs(treeOwner));
+    if (!treeOwner) {
       return nullptr;
     }
 
-    RefPtr<ContentParent> p = sAppContentParents->Get(manifestURL);
+    nsCOMPtr<nsIWebBrowserChrome> wbc = do_GetInterface(treeOwner);
+    if (!wbc) {
+      return nullptr;
+    }
+    uint32_t chromeFlags = 0;
+    wbc->GetChromeFlags(&chromeFlags);
 
-    if (!p && Preferences::GetBool("dom.ipc.reuse_parent_app")) {
-      nsAutoString parentAppManifestURL;
-      aFrameElement->GetAttr(kNameSpaceID_None,
-                             nsGkAtoms::parentapp, parentAppManifestURL);
-      nsAdoptingString systemAppManifestURL =
-        Preferences::GetString("b2g.system_manifest_url");
-      nsCOMPtr<nsIAppsService> appsService =
-        do_GetService(APPS_SERVICE_CONTRACTID);
-      if (!parentAppManifestURL.IsEmpty() &&
-        !parentAppManifestURL.Equals(systemAppManifestURL) &&
-        appsService) {
-        nsCOMPtr<mozIApplication> parentApp;
-        nsCOMPtr<mozIApplication> app;
-        appsService->GetAppByManifestURL(parentAppManifestURL,
-                                         getter_AddRefs(parentApp));
-        appsService->GetAppByManifestURL(manifestURL,
-                                         getter_AddRefs(app));
-
-        // Only let certified apps re-use the same process.
-        unsigned short parentAppStatus = 0;
-        unsigned short appStatus = 0;
-        if (app &&
-          NS_SUCCEEDED(app->GetAppStatus(&appStatus)) &&
-          appStatus == nsIPrincipal::APP_STATUS_CERTIFIED &&
-          parentApp &&
-          NS_SUCCEEDED(parentApp->GetAppStatus(&parentAppStatus)) &&
-          parentAppStatus == nsIPrincipal::APP_STATUS_CERTIFIED) {
-          // Check if we can re-use the process of the parent app.
-          p = sAppContentParents->Get(parentAppManifestURL);
-        }
-      }
+    nsCOMPtr<nsILoadContext> loadContext = do_QueryInterface(docShell);
+    if (loadContext && loadContext->UsePrivateBrowsing()) {
+      chromeFlags |= nsIWebBrowserChrome::CHROME_PRIVATE_WINDOW;
+    }
+    if (docShell->GetAffectPrivateSessionLifetime()) {
+      chromeFlags |= nsIWebBrowserChrome::CHROME_PRIVATE_LIFETIME;
     }
 
-    if (p) {
-      // Check that the process is still alive and set its priority.
-      // Hopefully the process won't die after this point, if this call
-      // succeeds.
-      if (!p->SetPriorityAndCheckIsAlive(initialPriority)) {
-        p = nullptr;
-      }
+    if (tabId == 0) {
+      return nullptr;
+    }
+    RefPtr<TabParent> tp(new TabParent(constructorSender, tabId,
+                                       aContext, chromeFlags));
+    tp->SetInitedByParent();
+
+    PBrowserParent* browser =
+    constructorSender->SendPBrowserConstructor(
+      // DeallocPBrowserParent() releases this ref.
+      tp.forget().take(), tabId,
+      aContext.AsIPCTabContext(),
+      chromeFlags,
+      constructorSender->ChildID(),
+      constructorSender->IsForBrowser());
+
+    if (aFreshProcess) {
+      Unused << browser->SendSetFreshProcess();
     }
 
-    reused = !!p;
-    if (!p) {
-      p = GetNewOrPreallocatedAppProcess(ownApp, initialPriority, nullptr,
-                                         &tookPreallocated);
-      MOZ_ASSERT(p);
-      sAppContentParents->Put(manifestURL, p);
+    if (browser) {
+      RefPtr<TabParent> constructedTabParent = TabParent::GetFrom(browser);
+      constructedTabParent->SetOwnerElement(aFrameElement);
+      return constructedTabParent;
     }
-    tabId = AllocateTabId(openerTabId, aContext.AsIPCTabContext(),
-                          p->ChildID());
-    parent = static_cast<nsIContentParent*>(p);
   }
-
-  if (!parent || (tabId == 0)) {
-    return nullptr;
-  }
-
-  uint32_t chromeFlags = 0;
-
-  RefPtr<TabParent> tp = new TabParent(parent, tabId, aContext, chromeFlags);
-  tp->SetInitedByParent();
-  PBrowserParent* browser = parent->SendPBrowserConstructor(
-    // DeallocPBrowserParent() releases this ref.
-    RefPtr<TabParent>(tp).forget().take(),
-    tabId,
-    aContext.AsIPCTabContext(),
-    chromeFlags,
-    parent->ChildID(),
-    parent->IsForApp(),
-    parent->IsForBrowser());
-
-  if (aFreshProcess) {
-    Unused << browser->SendSetFreshProcess();
-  }
-
-  if (browser) {
-    RefPtr<TabParent> constructedTabParent = TabParent::GetFrom(browser);
-    constructedTabParent->SetOwnerElement(aFrameElement);
-  }
-
-  if (isInContentProcess) {
-    // Just return directly without the following check in content process.
-    return TabParent::GetFrom(browser);
-  }
-
-  if (!browser) {
-    // We failed to actually start the PBrowser.  This can happen if the
-    // other process has already died.
-    if (!reused) {
-      // Don't leave a broken ContentParent in the hashtable.
-      parent->AsContentParent()->KillHard("CreateBrowserOrApp");
-      sAppContentParents->Remove(manifestURL);
-      parent = nullptr;
-    }
-
-    // If we took the preallocated process and it was already dead, try
-    // again with a non-preallocated process.  We can be sure this won't
-    // loop forever, because the next time through there will be no
-    // preallocated process to take.
-    if (tookPreallocated) {
-      return ContentParent::CreateBrowserOrApp(aContext, aFrameElement,
-                                               aOpenerContentParent);
-    }
-
-    // Otherwise just give up.
-    return nullptr;
-  }
-
-  return TabParent::GetFrom(browser);
+  return nullptr;
 }
 
 /*static*/ ContentBridgeParent*
@@ -1300,13 +1084,11 @@ ContentParent::CreateContentBridgeParent(const TabContext& aContext,
 
   ContentChild* child = ContentChild::GetSingleton();
   ContentParentId cpId;
-  bool isForApp;
   bool isForBrowser;
   if (!child->SendCreateChildProcess(aContext.AsIPCTabContext(),
                                      aPriority,
                                      aOpenerTabId,
                                      &cpId,
-                                     &isForApp,
                                      &isForBrowser,
                                      aTabId)) {
     return nullptr;
@@ -1319,7 +1101,6 @@ ContentParent::CreateContentBridgeParent(const TabContext& aContext,
   }
   ContentBridgeParent* parent = child->GetLastBridge();
   parent->SetChildID(cpId);
-  parent->SetIsForApp(isForApp);
   parent->SetIsForBrowser(isForBrowser);
   return parent;
 }
@@ -1482,48 +1263,12 @@ ContentParent::SetPriorityAndCheckIsAlive(ProcessPriority aPriority)
   return true;
 }
 
-// Helper for ContentParent::TransformPreallocatedIntoApp.
-static void
-TryGetNameFromManifestURL(const nsAString& aManifestURL,
-              nsAString& aName)
-{
-  aName.Truncate();
-  if (aManifestURL.IsEmpty() ||
-    aManifestURL == MAGIC_PREALLOCATED_APP_MANIFEST_URL) {
-    return;
-  }
-
-  nsCOMPtr<nsIAppsService> appsService = do_GetService(APPS_SERVICE_CONTRACTID);
-  NS_ENSURE_TRUE_VOID(appsService);
-
-  nsCOMPtr<mozIApplication> app;
-  appsService->GetAppByManifestURL(aManifestURL, getter_AddRefs(app));
-
-  if (!app) {
-    return;
-  }
-
-  app->GetName(aName);
-}
-
-void
-ContentParent::TransformPreallocatedIntoApp(ContentParent* aOpener,
-                                            const nsAString& aAppManifestURL)
-{
-  MOZ_ASSERT(IsPreallocated());
-  mMetamorphosed = true;
-  mOpener = aOpener;
-  mAppManifestURL = aAppManifestURL;
-  TryGetNameFromManifestURL(aAppManifestURL, mAppName);
-}
-
 void
 ContentParent::TransformPreallocatedIntoBrowser(ContentParent* aOpener)
 {
-  // Reset mAppManifestURL, mIsForBrowser and mOSPrivileges for browser.
+  // Reset mIsForBrowser and mOSPrivileges for browser.
   mMetamorphosed = true;
   mOpener = aOpener;
-  mAppManifestURL.Truncate();
   mIsForBrowser = true;
 }
 
@@ -1610,29 +1355,19 @@ ContentParent::ShutDownMessageManager()
 void
 ContentParent::MarkAsDead()
 {
-  if (!mAppManifestURL.IsEmpty()) {
-    if (sAppContentParents) {
-      sAppContentParents->Remove(mAppManifestURL);
-      if (!sAppContentParents->Count()) {
-        delete sAppContentParents;
-        sAppContentParents = nullptr;
-      }
-    }
-  } else {
-    if (sNonAppContentParents) {
-      sNonAppContentParents->RemoveElement(this);
-      if (!sNonAppContentParents->Length()) {
-        delete sNonAppContentParents;
-        sNonAppContentParents = nullptr;
-      }
+  if (sBrowserContentParents) {
+    sBrowserContentParents->RemoveElement(this);
+    if (!sBrowserContentParents->Length()) {
+      delete sBrowserContentParents;
+      sBrowserContentParents = nullptr;
     }
+  }
 
-    if (sLargeAllocationContentParents) {
-      sLargeAllocationContentParents->RemoveElement(this);
-      if (!sLargeAllocationContentParents->Length()) {
-        delete sLargeAllocationContentParents;
-        sLargeAllocationContentParents = nullptr;
-      }
+  if (sLargeAllocationContentParents) {
+    sLargeAllocationContentParents->RemoveElement(this);
+    if (!sLargeAllocationContentParents->Length()) {
+      delete sLargeAllocationContentParents;
+      sLargeAllocationContentParents = nullptr;
     }
   }
 
@@ -1870,17 +1605,6 @@ ContentParent::ActorDestroy(ActorDestroyReason why)
         CrashReporterParent* crashReporter =
           static_cast<CrashReporterParent*>(p);
 
-        // If we're an app process, always stomp the latest URI
-        // loaded in the child process with our manifest URL.  We
-        // would rather associate the crashes with apps than
-        // random child windows loaded in them.
-        //
-        // XXX would be nice if we could get both ...
-        if (!mAppManifestURL.IsEmpty()) {
-          crashReporter->AnnotateCrashReport(NS_LITERAL_CSTRING("URL"),
-                                             NS_ConvertUTF16toUTF8(mAppManifestURL));
-        }
-
         // if mCreatedPairedMinidumps is true, we've already generated
         // parent/child dumps for dekstop crashes.
         if (!mCreatedPairedMinidumps) {
@@ -1972,7 +1696,7 @@ ContentParent::NotifyTabDestroying(const TabId& aTabId,
         return;
     }
 
-    uint32_t numberOfParents = sNonAppContentParents ? sNonAppContentParents->Length() : 0;
+    uint32_t numberOfParents = sBrowserContentParents ? sBrowserContentParents->Length() : 0;
     int32_t processesToKeepAlive = Preferences::GetInt("dom.ipc.keepProcessesAlive", 0);
     if (!cp->mLargeAllocationProcess && static_cast<int32_t>(numberOfParents) <= processesToKeepAlive) {
       return;
@@ -2029,7 +1753,7 @@ ContentParent::NotifyTabDestroyed(const TabId& aTabId,
 
   // We might want to keep alive some content processes for testing, because of performance
   // reasons, but we don't want to alter behavior if the pref is not set.
-  uint32_t numberOfParents = sNonAppContentParents ? sNonAppContentParents->Length() : 0;
+  uint32_t numberOfParents = sBrowserContentParents ? sBrowserContentParents->Length() : 0;
   int32_t processesToKeepAlive = Preferences::GetInt("dom.ipc.keepProcessesAlive", 0);
   bool shouldKeepAliveAny = !mLargeAllocationProcess && processesToKeepAlive > 0;
   bool shouldKeepAliveThis = shouldKeepAliveAny && static_cast<int32_t>(numberOfParents) <= processesToKeepAlive;
@@ -2118,20 +1842,20 @@ ContentParent::LaunchSubprocess(ProcessPriority aInitialPriority /* = PROCESS_PR
   return true;
 }
 
-ContentParent::ContentParent(mozIApplication* aApp,
-                             ContentParent* aOpener,
+ContentParent::ContentParent(ContentParent* aOpener,
                              bool aIsForBrowser,
                              bool aIsForPreallocated)
   : nsIContentParent()
   , mOpener(aOpener)
   , mIsForBrowser(aIsForBrowser)
+  , mIsPreallocated(aIsForPreallocated)
   , mLargeAllocationProcess(false)
 {
   InitializeMembers();  // Perform common initialization.
 
-  // No more than one of !!aApp, aIsForBrowser, aIsForPreallocated should be
+  // No more than one of aIsForBrowser and aIsForPreallocated should be
   // true.
-  MOZ_ASSERT(!!aApp + aIsForBrowser + aIsForPreallocated <= 1);
+  MOZ_ASSERT(aIsForBrowser + aIsForPreallocated <= 1);
 
   mMetamorphosed = true;
 
@@ -2141,13 +1865,6 @@ ContentParent::ContentParent(mozIApplication* aApp,
   }
   sContentParents->insertBack(this);
 
-  if (aApp) {
-    aApp->GetManifestURL(mAppManifestURL);
-    aApp->GetName(mAppName);
-  } else if (aIsForPreallocated) {
-    mAppManifestURL = MAGIC_PREALLOCATED_APP_MANIFEST_URL;
-  }
-
   // From this point on, NS_WARNING, NS_ASSERTION, etc. should print out the
   // PID along with the warning.
   nsDebugImpl::SetMultiprocessMode("Parent");
@@ -2174,19 +1891,10 @@ ContentParent::~ContentParent()
 
   // We should be removed from all these lists in ActorDestroy.
   MOZ_ASSERT(!sPrivateContent || !sPrivateContent->Contains(this));
-  if (mAppManifestURL.IsEmpty()) {
-    MOZ_ASSERT((!sNonAppContentParents ||
-                !sNonAppContentParents->Contains(this)) &&
-               (!sLargeAllocationContentParents ||
-                !sLargeAllocationContentParents->Contains(this)));
-  } else {
-    // In general, we expect sAppContentParents->Get(mAppManifestURL) to be
-    // nullptr.  But it could be that we created another ContentParent for
-    // this app after we did this->ActorDestroy(), so the right check is
-    // that sAppContentParents->Get(mAppManifestURL) != this.
-    MOZ_ASSERT(!sAppContentParents ||
-               sAppContentParents->Get(mAppManifestURL) != this);
-  }
+  MOZ_ASSERT((!sBrowserContentParents ||
+              !sBrowserContentParents->Contains(this)) &&
+             (!sLargeAllocationContentParents ||
+              !sLargeAllocationContentParents->Contains(this)));
 }
 
 void
@@ -2356,12 +2064,6 @@ ContentParent::IsAlive() const
   return mIsAlive;
 }
 
-bool
-ContentParent::IsForApp() const
-{
-  return !mAppManifestURL.IsEmpty();
-}
-
 int32_t
 ContentParent::Pid() const
 {
@@ -2891,10 +2593,9 @@ ContentParent::AllocPProcessHangMonitorParent(Transport* aTransport,
 
 mozilla::ipc::IPCResult
 ContentParent::RecvGetProcessAttributes(ContentParentId* aCpId,
-                                        bool* aIsForApp, bool* aIsForBrowser)
+                                        bool* aIsForBrowser)
 {
   *aCpId = mChildID;
-  *aIsForApp = IsForApp();
   *aIsForBrowser = mIsForBrowser;
 
   return IPC_OK();
@@ -2986,14 +2687,12 @@ ContentParent::AllocPBrowserParent(const TabId& aTabId,
                                    const IPCTabContext& aContext,
                                    const uint32_t& aChromeFlags,
                                    const ContentParentId& aCpId,
-                                   const bool& aIsForApp,
                                    const bool& aIsForBrowser)
 {
   return nsIContentParent::AllocPBrowserParent(aTabId,
                                                aContext,
                                                aChromeFlags,
                                                aCpId,
-                                               aIsForApp,
                                                aIsForBrowser);
 }
 
@@ -3143,7 +2842,7 @@ ContentParent::KillHard(const char* aReason)
 bool
 ContentParent::IsPreallocated() const
 {
-  return mAppManifestURL == MAGIC_PREALLOCATED_APP_MANIFEST_URL;
+  return mIsPreallocated;
 }
 
 void
@@ -3156,11 +2855,6 @@ ContentParent::FriendlyName(nsAString& aName, bool aAnonymize)
     aName.AssignLiteral("Browser");
   } else if (aAnonymize) {
     aName.AssignLiteral("<anonymized-name>");
-  } else if (!mAppName.IsEmpty()) {
-    aName = mAppName;
-  } else if (!mAppManifestURL.IsEmpty()) {
-    aName.AssignLiteral("Unknown app: ");
-    aName.Append(mAppManifestURL);
   } else {
     aName.AssignLiteral("???");
   }
@@ -4118,7 +3812,6 @@ ContentParent::SendPBrowserConstructor(PBrowserParent* aActor,
                                        const IPCTabContext& aContext,
                                        const uint32_t& aChromeFlags,
                                        const ContentParentId& aCpId,
-                                       const bool& aIsForApp,
                                        const bool& aIsForBrowser)
 {
   return PContentParent::SendPBrowserConstructor(aActor,
@@ -4126,7 +3819,6 @@ ContentParent::SendPBrowserConstructor(PBrowserParent* aActor,
                                                  aContext,
                                                  aChromeFlags,
                                                  aCpId,
-                                                 aIsForApp,
                                                  aIsForBrowser);
 }
 
@@ -4271,12 +3963,9 @@ ContentParent::RecvRecordingDeviceEvents(const nsString& aRecordingStatus,
     // recording-device-ipc-events needs to gather more information from content process
     RefPtr<nsHashPropertyBag> props = new nsHashPropertyBag();
     props->SetPropertyAsUint64(NS_LITERAL_STRING("childID"), ChildID());
-    props->SetPropertyAsBool(NS_LITERAL_STRING("isApp"), IsForApp());
     props->SetPropertyAsBool(NS_LITERAL_STRING("isAudio"), aIsAudio);
     props->SetPropertyAsBool(NS_LITERAL_STRING("isVideo"), aIsVideo);
-
-    nsString requestURL = IsForApp() ? AppManifestURL() : aPageURL;
-    props->SetPropertyAsAString(NS_LITERAL_STRING("requestURL"), requestURL);
+    props->SetPropertyAsAString(NS_LITERAL_STRING("requestURL"), aPageURL);
 
     obs->NotifyObservers((nsIPropertyBag2*) props,
                          "recording-device-ipc-events",
@@ -4731,7 +4420,7 @@ ContentParent::RecvCreateWindow(PBrowserParent* aThisTab,
     thisTabParent = TabParent::GetFrom(aThisTab);
   }
 
-  if (NS_WARN_IF(thisTabParent && thisTabParent->IsMozBrowserOrApp())) {
+  if (NS_WARN_IF(thisTabParent && thisTabParent->IsMozBrowser())) {
     return IPC_FAIL_NO_REASON(this);
   }
 
diff --git a/dom/ipc/ContentParent.h b/dom/ipc/ContentParent.h
index 033cec1b0236..13c0799ce0f9 100644
--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -32,7 +32,6 @@
 
 #define CHILD_PROCESS_SHUTDOWN_MESSAGE NS_LITERAL_STRING("child-process-shutdown")
 
-class mozIApplication;
 class nsConsoleService;
 class nsICycleCollectorLogSink;
 class nsIDumpGCAndCCLogsCallback;
@@ -149,10 +148,10 @@ public:
    * associated.
    */
   static TabParent*
-  CreateBrowserOrApp(const TabContext& aContext,
-                     Element* aFrameElement,
-                     ContentParent* aOpenerContentParent,
-                     bool aFreshProcess = false);
+  CreateBrowser(const TabContext& aContext,
+                Element* aFrameElement,
+                ContentParent* aOpenerContentParent,
+                bool aFreshProcess = false);
 
   static void GetAll(nsTArray<ContentParent*>& aArray);
 
@@ -240,7 +239,6 @@ public:
                                                          const hal::ProcessPriority& aPriority,
                                                          const TabId& aOpenerTabId,
                                                          ContentParentId* aCpId,
-                                                         bool* aIsForApp,
                                                          bool* aIsForBrowser,
                                                          TabId* aTabId) override;
 
@@ -329,8 +327,6 @@ public:
 
   bool IsAlive() const;
 
-  virtual bool IsForApp() const override;
-
   virtual bool IsForBrowser() const override
   {
     return mIsForBrowser;
@@ -363,8 +359,6 @@ public:
 
   ContentParentId ChildID() const override { return mChildID; }
 
-  const nsString& AppManifestURL() const { return mAppManifestURL; }
-
   bool IsPreallocated() const;
 
   /**
@@ -561,8 +555,7 @@ protected:
   void OnCompositorUnexpectedShutdown() override;
 
 private:
-  static nsDataHashtable<nsStringHashKey, ContentParent*> *sAppContentParents;
-  static nsTArray<ContentParent*>* sNonAppContentParents;
+  static nsTArray<ContentParent*>* sBrowserContentParents;
   static nsTArray<ContentParent*>* sLargeAllocationContentParents;
   static nsTArray<ContentParent*>* sPrivateContent;
   static StaticAutoPtr<LinkedList<ContentParent> > sContentParents;
@@ -570,15 +563,6 @@ private:
   static void JoinProcessesIOThread(const nsTArray<ContentParent*>* aProcesses,
                                     Monitor* aMonitor, bool* aDone);
 
-  // Take the preallocated process and transform it into a "real" app process,
-  // for the specified manifest URL.  If there is no preallocated process (or
-  // if it's dead), create a new one and set aTookPreAllocated to false.
-  static already_AddRefed<ContentParent>
-  GetNewOrPreallocatedAppProcess(mozIApplication* aApp,
-                                 hal::ProcessPriority aInitialPriority,
-                                 ContentParent* aOpener,
-                                 /*out*/ bool* aTookPreAllocated = nullptr);
-
   static hal::ProcessPriority GetInitialProcessPriority(Element* aFrameElement);
 
   static ContentBridgeParent* CreateContentBridgeParent(const TabContext& aContext,
@@ -594,16 +578,14 @@ private:
       const IPCTabContext& context,
       const uint32_t& chromeFlags,
       const ContentParentId& aCpId,
-      const bool& aIsForApp,
       const bool& aIsForBrowser) override;
   using PContentParent::SendPTestShellConstructor;
 
   FORWARD_SHMEM_ALLOCATOR_TO(PContentParent)
 
-  // No more than one of !!aApp, aIsForBrowser, and aIsForPreallocated may be
+  // No more than one of aIsForBrowser, and aIsForPreallocated may be
   // true.
-  ContentParent(mozIApplication* aApp,
-                ContentParent* aOpener,
+  ContentParent(ContentParent* aOpener,
                 bool aIsForBrowser,
                 bool aIsForPreallocated);
 
@@ -625,7 +607,7 @@ private:
 
   // Some information could be sent to content very early, it
   // should be send from this function. This function should only be
-  // called after the process has been transformed to app or browser.
+  // called after the process has been transformed to browser.
   void ForwardKnownInfo();
 
   // Set the child process's priority and then check whether the child is
@@ -634,11 +616,6 @@ private:
   // unlikely that the process will be killed after this point.
   bool SetPriorityAndCheckIsAlive(hal::ProcessPriority aPriority);
 
-  // Transform a pre-allocated app process into a "real" app
-  // process, for the specified manifest URL.
-  void TransformPreallocatedIntoApp(ContentParent* aOpener,
-                                    const nsAString& aAppManifestURL);
-
   // Transform a pre-allocated app process into a browser process. If this
   // returns false, the child process has died.
   void TransformPreallocatedIntoBrowser(ContentParent* aOpener);
@@ -701,7 +678,6 @@ private:
                                  ProcessId aOtherProcess) override;
 
   virtual mozilla::ipc::IPCResult RecvGetProcessAttributes(ContentParentId* aCpId,
-                                                           bool* aIsForApp,
                                                            bool* aIsForBrowser) override;
 
   virtual mozilla::ipc::IPCResult
@@ -724,7 +700,6 @@ private:
                                               const IPCTabContext& aContext,
                                               const uint32_t& aChromeFlags,
                                               const ContentParentId& aCpId,
-                                              const bool& aIsForApp,
                                               const bool& aIsForBrowser) override;
 
   virtual bool DeallocPBrowserParent(PBrowserParent* frame) override;
@@ -1102,17 +1077,8 @@ private:
   ContentParentId mChildID;
   int32_t mGeolocationWatchID;
 
-  nsString mAppManifestURL;
-
   nsCString mKillHardAnnotation;
 
-  /**
-   * We cache mAppName instead of looking it up using mAppManifestURL when we
-   * need it because it turns out that getting an app from the apps service is
-   * expensive.
-   */
-  nsString mAppName;
-
   // After we initiate shutdown, we also start a timer to ensure
   // that even content processes that are 100% blocked (say from
   // SIGSTOP), are still killed eventually.  This task enforces that
@@ -1128,12 +1094,13 @@ private:
   // through.
   bool mIsAlive;
 
-  // True only the if process is already a browser or app or has
+  // True only the if process is already a browser or has
   // been transformed into one.
   bool mMetamorphosed;
 
   bool mSendPermissionUpdates;
   bool mIsForBrowser;
+  bool mIsPreallocated;
 
   // These variables track whether we've called Close() and KillHard() on our
   // channel.
diff --git a/dom/ipc/ContentProcessManager.cpp b/dom/ipc/ContentProcessManager.cpp
index 02fdcba34ded..334e9c99755d 100644
--- a/dom/ipc/ContentProcessManager.cpp
+++ b/dom/ipc/ContentProcessManager.cpp
@@ -354,19 +354,5 @@ ContentProcessManager::GetTabParentsByProcessId(const ContentParentId& aChildCpI
   return Move(tabIdList);
 }
 
-uint32_t
-ContentProcessManager::GetAppIdByProcessAndTabId(const ContentParentId& aChildCpId,
-                                                 const TabId& aChildTabId)
-{
-  uint32_t appId = nsIScriptSecurityManager::NO_APP_ID;
-  if (aChildCpId && aChildTabId) {
-    TabContext tabContext;
-    if (GetTabContextByProcessAndTabId(aChildCpId, aChildTabId, &tabContext)) {
-      appId = tabContext.OwnOrContainingAppId();
-    }
-  }
-  return appId;
-}
-
 } // namespace dom
 } // namespace mozilla
diff --git a/dom/ipc/ContentProcessManager.h b/dom/ipc/ContentProcessManager.h
index cc6d8bd8b89e..be92f4cd874c 100644
--- a/dom/ipc/ContentProcessManager.h
+++ b/dom/ipc/ContentProcessManager.h
@@ -143,15 +143,6 @@ public:
   GetTopLevelTabParentByProcessAndTabId(const ContentParentId& aChildCpId,
                                         const TabId& aChildTabId);
 
-  /**
-   * Return appId by given TabId and ContentParentId.
-   * It will return nsIScriptSecurityManager::NO_APP_ID
-   * if the given tab is not an app.
-   */
-  uint32_t
-  GetAppIdByProcessAndTabId(const ContentParentId& aChildCpId,
-                            const TabId& aChildTabId);
-
 private:
   static StaticAutoPtr<ContentProcessManager> sSingleton;
   TabId mUniqueId;
diff --git a/dom/ipc/PContent.ipdl b/dom/ipc/PContent.ipdl
index 45da2867bdfe..060fc8b9f180 100644
--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -391,27 +391,20 @@ both:
     // The child creates the PBrowser as part of
     // TabChild::BrowserFrameProvideWindow (which happens when the child's
     // content calls window.open()), and the parent creates the PBrowser as part
-    // of ContentParent::CreateBrowserOrApp.
+    // of ContentParent::CreateBrowser.
     //
-    // When the parent constructs a PBrowser, the child trusts the app token and
-    // other attributes it receives from the parent.  In that case, the
-    // context should be FrameIPCTabContext.
+    // When the parent constructs a PBrowser, the child trusts the attributes it
+    // receives from the parent.  In that case, the context should be
+    // FrameIPCTabContext.
     //
-    // When the child constructs a PBrowser, the parent doesn't trust the app
-    // token it receives from the child.  In this case, context must have type
-    // PopupIPCTabContext.  The browser created using a PopupIPCTabContext has
-    // the opener PBrowser's app-id and containing-app-id.  The parent checks
-    // that if the opener is a browser element, the context is also for a
-    // browser element.
-    //
-    // This allows the parent to prevent a malicious child from escalating its
-    // privileges by requesting a PBrowser corresponding to a highly-privileged
-    // app; the child can only request privileges for an app which the child has
-    // access to (in the form of a TabChild).
+    // When the child constructs a PBrowser, the parent doesn't trust the
+    // attributes it receives from the child.  In this case, context must have
+    // type PopupIPCTabContext.  The parent checks that if the opener is a
+    // browser element, the context is also for a browser element.
     //
     // Keep the last 3 attributes in sync with GetProcessAttributes!
     async PBrowser(TabId tabId, IPCTabContext context, uint32_t chromeFlags,
-                   ContentParentId cpId, bool isForApp, bool isForBrowser);
+                   ContentParentId cpId, bool isForBrowser);
 
     async PBlob(BlobConstructorParams params);
 
@@ -678,15 +671,13 @@ parent:
      * startup.  (The message is sync to allow the content process to
      * control when it receives the information.)
      *
-     * |id| is a unique ID among all subprocesses.  When |isForApp &&
-     * isForBrowser|, we're loading <browser> for an app.  When
-     * |isForBrowser|, we're loading <browser>.  When |!isForApp &&
-     * !isForBrowser|, we're probably loading <xul:browser remote>.
+     * |id| is a unique ID among all subprocesses. When
+     * |isForBrowser|, we're loading <browser> or <xul:browser remote>.
      *
      * Keep the return values in sync with PBrowser()!
      */
     sync GetProcessAttributes()
-        returns (ContentParentId cpId, bool isForApp, bool isForBrowser);
+        returns (ContentParentId cpId, bool isForBrowser);
     sync GetXPCOMProcessAttributes()
         returns (bool isOffline, bool isConnected, bool isLangRTL,
                  bool haveBidiKeyboards, nsString[] dictionaries,
@@ -697,7 +688,7 @@ parent:
     sync CreateChildProcess(IPCTabContext context,
                             ProcessPriority priority,
                             TabId openerTabId)
-        returns (ContentParentId cpId, bool isForApp, bool isForBrowser, TabId tabId);
+        returns (ContentParentId cpId, bool isForBrowser, TabId tabId);
     sync BridgeToChildProcess(ContentParentId cpId);
 
     async CreateGMPService();
diff --git a/dom/ipc/PContentBridge.ipdl b/dom/ipc/PContentBridge.ipdl
index 72f8391781be..745c558f6a60 100644
--- a/dom/ipc/PContentBridge.ipdl
+++ b/dom/ipc/PContentBridge.ipdl
@@ -55,7 +55,7 @@ both:
     // Both the parent and the child can construct the PBrowser.
     // See the comment in PContent::PBrowser().
     async PBrowser(TabId tabId, IPCTabContext context, uint32_t chromeFlags,
-                   ContentParentId cpId, bool isForApp, bool isForBrowser);
+                   ContentParentId cpId, bool isForBrowser);
 
     async PBlob(BlobConstructorParams params);
 
diff --git a/dom/ipc/PTabContext.ipdlh b/dom/ipc/PTabContext.ipdlh
index 507ef59d9698..ac270d777149 100644
--- a/dom/ipc/PTabContext.ipdlh
+++ b/dom/ipc/PTabContext.ipdlh
@@ -39,9 +39,6 @@ struct FrameIPCTabContext
   // The originAttributes dictionary.
   DocShellOriginAttributes originAttributes;
 
-  // The ID of the app containing this app/browser frame, if applicable.
-  uint32_t frameOwnerAppId;
-
   // Whether this is a mozbrowser frame.  <iframe mozbrowser mozapp> and
   // <xul:browser> are not considered to be mozbrowser frames.
   bool isMozBrowserElement;
diff --git a/dom/ipc/ProcessPriorityManager.cpp b/dom/ipc/ProcessPriorityManager.cpp
index 80839796dd53..6182ac7faaaa 100644
--- a/dom/ipc/ProcessPriorityManager.cpp
+++ b/dom/ipc/ProcessPriorityManager.cpp
@@ -861,10 +861,10 @@ ParticularProcessPriorityManager::OnRemoteBrowserFrameShown(nsISupports* aSubjec
     return;
   }
 
-  // Ignore notifications that aren't from a BrowserOrApp
-  bool isMozBrowserOrApp;
-  fl->GetOwnerIsMozBrowserOrAppFrame(&isMozBrowserOrApp);
-  if (isMozBrowserOrApp) {
+  // Ignore notifications that aren't from a Browser
+  bool isMozBrowser;
+  fl->GetOwnerIsMozBrowserFrame(&isMozBrowser);
+  if (isMozBrowser) {
     ResetPriority();
   }
 
diff --git a/dom/ipc/TabChild.cpp b/dom/ipc/TabChild.cpp
index 9f7fc8c1f1a2..5da580fa4b28 100644
--- a/dom/ipc/TabChild.cpp
+++ b/dom/ipc/TabChild.cpp
@@ -417,7 +417,7 @@ TabChild::Create(nsIContentChild* aManager,
 {
     if (sPreallocatedTab &&
         sPreallocatedTab->mChromeFlags == aChromeFlags &&
-        aContext.IsMozBrowserOrApp()) {
+        aContext.IsMozBrowser()) {
 
         RefPtr<TabChild> child = sPreallocatedTab.get();
         sPreallocatedTab = nullptr;
@@ -792,8 +792,7 @@ TabChild::UpdateFrameType()
 
   // TODO: Bug 1252794 - remove frameType from nsIDocShell.idl
   docShell->SetFrameType(IsMozBrowserElement() ? nsIDocShell::FRAME_TYPE_BROWSER :
-                           HasOwnApp() ? nsIDocShell::FRAME_TYPE_APP :
-                             nsIDocShell::FRAME_TYPE_REGULAR);
+                           nsIDocShell::FRAME_TYPE_REGULAR);
 }
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(TabChild)
@@ -1103,11 +1102,11 @@ TabChild::ProvideWindow(mozIDOMWindowProxy* aParent,
 {
     *aReturn = nullptr;
 
-    // If aParent is inside an <iframe mozbrowser> or <iframe mozapp> and this
-    // isn't a request to open a modal-type window, we're going to create a new
-    // <iframe mozbrowser/mozapp> and return its window here.
+    // If aParent is inside an <iframe mozbrowser> and this isn't a request to
+    // open a modal-type window, we're going to create a new <iframe mozbrowser>
+    // and return its window here.
     nsCOMPtr<nsIDocShell> docshell = do_GetInterface(aParent);
-    bool iframeMoz = (docshell && docshell->GetIsInMozBrowserOrApp() &&
+    bool iframeMoz = (docshell && docshell->GetIsInMozBrowser() &&
                       !(aChromeFlags & (nsIWebBrowserChrome::CHROME_MODAL |
                                         nsIWebBrowserChrome::CHROME_OPENAS_DIALOG |
                                         nsIWebBrowserChrome::CHROME_OPENAS_CHROME)));
@@ -1214,24 +1213,6 @@ TabChild::~TabChild()
   }
 }
 
-void
-TabChild::SetProcessNameToAppName()
-{
-  nsCOMPtr<mozIApplication> app = GetOwnApp();
-  if (!app) {
-    return;
-  }
-
-  nsAutoString appName;
-  nsresult rv = app->GetName(appName);
-  if (NS_FAILED(rv)) {
-    NS_WARNING("Failed to retrieve app name");
-    return;
-  }
-
-  ContentChild::GetSingleton()->SetProcessName(appName, true);
-}
-
 mozilla::ipc::IPCResult
 TabChild::RecvLoadURL(const nsCString& aURI,
                       const ShowInfo& aInfo)
@@ -1243,8 +1224,6 @@ TabChild::RecvLoadURL(const nsCString& aURI,
     }
 
     ApplyShowInfo(aInfo);
-
-    SetProcessNameToAppName();
   }
 
   nsresult rv =
@@ -1289,7 +1268,7 @@ TabChild::ApplyShowInfo(const ShowInfo& aInfo)
   nsCOMPtr<nsIDocShell> docShell = do_GetInterface(WebNavigation());
   if (docShell) {
     nsCOMPtr<nsIDocShellTreeItem> item = do_GetInterface(docShell);
-    if (IsMozBrowserOrApp()) {
+    if (IsMozBrowser()) {
       // B2G allows window.name to be set by changing the name attribute on the
       // <iframe mozbrowser> element. window.open calls cause this attribute to
       // be set to the correct value. A normal <xul:browser> element has no such
@@ -2218,7 +2197,7 @@ TabChild::RecvSwappedWithOtherRemoteLoader(const IPCTabContext& aContext)
   // Ignore previous value of mTriedBrowserInit since owner content has changed.
   mTriedBrowserInit = true;
   // Initialize the child side of the browser element machinery, if appropriate.
-  if (IsMozBrowserOrApp()) {
+  if (IsMozBrowser()) {
     RecvLoadRemoteScript(BROWSER_ELEMENT_CHILD_SCRIPT, true);
   }
 
@@ -2578,7 +2557,7 @@ TabChild::InitTabChildGlobal(FrameScriptLoading aScriptLoading)
     mTriedBrowserInit = true;
     // Initialize the child side of the browser element machinery,
     // if appropriate.
-    if (IsMozBrowserOrApp()) {
+    if (IsMozBrowser()) {
       RecvLoadRemoteScript(BROWSER_ELEMENT_CHILD_SCRIPT, true);
     }
   }
diff --git a/dom/ipc/TabChild.h b/dom/ipc/TabChild.h
index 76308bb3d9e7..0bf9cfc7dc9e 100644
--- a/dom/ipc/TabChild.h
+++ b/dom/ipc/TabChild.h
@@ -734,8 +734,6 @@ private:
 
   void DestroyWindow();
 
-  void SetProcessNameToAppName();
-
   void ApplyShowInfo(const ShowInfo& aInfo);
 
   bool HasValidInnerSize();
diff --git a/dom/ipc/TabContext.cpp b/dom/ipc/TabContext.cpp
index b36dbc5ebc2e..43b2d5b52c38 100644
--- a/dom/ipc/TabContext.cpp
+++ b/dom/ipc/TabContext.cpp
@@ -8,7 +8,6 @@
 #include "mozilla/dom/PTabContext.h"
 #include "mozilla/dom/TabParent.h"
 #include "mozilla/dom/TabChild.h"
-#include "nsIAppsService.h"
 #include "nsIScriptSecurityManager.h"
 #include "nsServiceManagerUtils.h"
 
@@ -24,7 +23,7 @@ TabContext::TabContext()
   : mIsPrerendered(false)
   , mInitialized(false)
   , mIsMozBrowserElement(false)
-  , mContainingAppId(NO_APP_ID)
+  , mOriginAttributes()
   , mShowAccelerators(UIStateChangeType_NoChange)
   , mShowFocusRings(UIStateChangeType_NoChange)
 {
@@ -43,111 +42,9 @@ TabContext::IsIsolatedMozBrowserElement() const
 }
 
 bool
-TabContext::IsMozBrowserOrApp() const
+TabContext::IsMozBrowser() const
 {
-  return HasOwnApp() || IsMozBrowserElement();
-}
-
-uint32_t
-TabContext::OwnAppId() const
-{
-  return mOriginAttributes.mAppId;
-}
-
-already_AddRefed<mozIApplication>
-TabContext::GetOwnApp() const
-{
-  nsCOMPtr<mozIApplication> ownApp = mOwnApp;
-  return ownApp.forget();
-}
-
-bool
-TabContext::HasOwnApp() const
-{
-  nsCOMPtr<mozIApplication> ownApp = GetOwnApp();
-  return !!ownApp;
-}
-
-uint32_t
-TabContext::BrowserOwnerAppId() const
-{
-  if (IsMozBrowserElement()) {
-    return mContainingAppId;
-  }
-  return NO_APP_ID;
-}
-
-already_AddRefed<mozIApplication>
-TabContext::GetBrowserOwnerApp() const
-{
-  nsCOMPtr<mozIApplication> ownerApp;
-  if (IsMozBrowserElement()) {
-    ownerApp = mContainingApp;
-  }
-  return ownerApp.forget();
-}
-
-bool
-TabContext::HasBrowserOwnerApp() const
-{
-  nsCOMPtr<mozIApplication> ownerApp = GetBrowserOwnerApp();
-  return !!ownerApp;
-}
-
-uint32_t
-TabContext::AppOwnerAppId() const
-{
-  if (HasOwnApp()) {
-    return mContainingAppId;
-  }
-  return NO_APP_ID;
-}
-
-already_AddRefed<mozIApplication>
-TabContext::GetAppOwnerApp() const
-{
-  nsCOMPtr<mozIApplication> ownerApp;
-  if (HasOwnApp()) {
-    ownerApp = mContainingApp;
-  }
-  return ownerApp.forget();
-}
-
-bool
-TabContext::HasAppOwnerApp() const
-{
-  nsCOMPtr<mozIApplication> ownerApp = GetAppOwnerApp();
-  return !!ownerApp;
-}
-
-uint32_t
-TabContext::OwnOrContainingAppId() const
-{
-  if (HasOwnApp()) {
-    return mOriginAttributes.mAppId;
-  }
-
-  return mContainingAppId;
-}
-
-already_AddRefed<mozIApplication>
-TabContext::GetOwnOrContainingApp() const
-{
-  nsCOMPtr<mozIApplication> ownOrContainingApp;
-  if (HasOwnApp()) {
-    ownOrContainingApp = mOwnApp;
-  } else {
-    ownOrContainingApp = mContainingApp;
-  }
-
-  return ownOrContainingApp.forget();
-}
-
-bool
-TabContext::HasOwnOrContainingApp() const
-{
-  nsCOMPtr<mozIApplication> ownOrContainingApp = GetOwnOrContainingApp();
-  return !!ownOrContainingApp;
+  return IsMozBrowserElement();
 }
 
 bool
@@ -175,9 +72,7 @@ TabContext::UpdateTabContextAfterSwap(const TabContext& aContext)
 
   // The only permissable change is to `mIsMozBrowserElement`.  All other fields
   // must match for the change to be accepted.
-  if (aContext.OwnAppId() != OwnAppId() ||
-      aContext.mContainingAppId != mContainingAppId ||
-      aContext.mOriginAttributes != mOriginAttributes) {
+  if (aContext.mOriginAttributes != mOriginAttributes) {
     return false;
   }
 
@@ -212,8 +107,6 @@ TabContext::ShowFocusRings() const
 bool
 TabContext::SetTabContext(bool aIsMozBrowserElement,
                           bool aIsPrerendered,
-                          mozIApplication* aOwnApp,
-                          mozIApplication* aAppFrameOwnerApp,
                           UIStateChangeType aShowAccelerators,
                           UIStateChangeType aShowFocusRings,
                           const DocShellOriginAttributes& aOriginAttributes,
@@ -221,34 +114,13 @@ TabContext::SetTabContext(bool aIsMozBrowserElement,
 {
   NS_ENSURE_FALSE(mInitialized, false);
 
-  // Get ids for both apps and only write to our member variables after we've
-  // verified that this worked.
-  uint32_t ownAppId = NO_APP_ID;
-  if (aOwnApp) {
-    nsresult rv = aOwnApp->GetLocalId(&ownAppId);
-    NS_ENSURE_SUCCESS(rv, false);
-    NS_ENSURE_TRUE(ownAppId != NO_APP_ID, false);
-  }
-
-  uint32_t containingAppId = NO_APP_ID;
-  if (aAppFrameOwnerApp) {
-    nsresult rv = aAppFrameOwnerApp->GetLocalId(&containingAppId);
-    NS_ENSURE_SUCCESS(rv, false);
-    NS_ENSURE_TRUE(containingAppId != NO_APP_ID, false);
-  }
-
   // Veryify that app id matches mAppId passed in originAttributes
-  MOZ_RELEASE_ASSERT((aOwnApp && aOriginAttributes.mAppId == ownAppId) ||
-                     (aAppFrameOwnerApp && aOriginAttributes.mAppId == containingAppId) ||
-                     aOriginAttributes.mAppId == NO_APP_ID);
+  MOZ_RELEASE_ASSERT(aOriginAttributes.mAppId == NO_APP_ID);
 
   mInitialized = true;
   mIsMozBrowserElement = aIsMozBrowserElement;
   mIsPrerendered = aIsPrerendered;
   mOriginAttributes = aOriginAttributes;
-  mContainingAppId = containingAppId;
-  mOwnApp = aOwnApp;
-  mContainingApp = aAppFrameOwnerApp;
   mPresentationURL = aPresentationURL;
   mShowAccelerators = aShowAccelerators;
   mShowFocusRings = aShowFocusRings;
@@ -259,7 +131,6 @@ IPCTabContext
 TabContext::AsIPCTabContext() const
 {
   return IPCTabContext(FrameIPCTabContext(mOriginAttributes,
-                                          mContainingAppId,
                                           mIsMozBrowserElement,
                                           mIsPrerendered,
                                           mPresentationURL,
@@ -267,24 +138,11 @@ TabContext::AsIPCTabContext() const
                                           mShowFocusRings));
 }
 
-static already_AddRefed<mozIApplication>
-GetAppForId(uint32_t aAppId)
-{
-  nsCOMPtr<nsIAppsService> appsService = do_GetService(APPS_SERVICE_CONTRACTID);
-  NS_ENSURE_TRUE(appsService, nullptr);
-
-  nsCOMPtr<mozIApplication> app;
-  appsService->GetAppByLocalId(aAppId, getter_AddRefs(app));
-
-  return app.forget();
-}
-
 MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
   : mInvalidReason(nullptr)
 {
   bool isMozBrowserElement = false;
   bool isPrerendered = false;
-  uint32_t containingAppId = NO_APP_ID;
   DocShellOriginAttributes originAttributes;
   nsAutoString presentationURL;
   UIStateChangeType showAccelerators = UIStateChangeType_NoChange;
@@ -335,11 +193,6 @@ MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
       // opener app.
       isMozBrowserElement = ipcContext.isMozBrowserElement();
       originAttributes = context->mOriginAttributes;
-      if (isMozBrowserElement) {
-        containingAppId = context->OwnOrContainingAppId();
-      } else {
-        containingAppId = context->mContainingAppId;
-      }
       break;
     }
     case IPCTabContext::TFrameIPCTabContext: {
@@ -348,7 +201,6 @@ MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
 
       isMozBrowserElement = ipcContext.isMozBrowserElement();
       isPrerendered = ipcContext.isPrerendered();
-      containingAppId = ipcContext.frameOwnerAppId();
       presentationURL = ipcContext.presentationURL();
       showAccelerators = ipcContext.showAccelerators();
       showFocusRings = ipcContext.showFocusRings();
@@ -369,7 +221,6 @@ MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
         return;
       }
 
-      containingAppId = NO_APP_ID;
       break;
     }
     default: {
@@ -377,28 +228,9 @@ MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
     }
   }
 
-  nsCOMPtr<mozIApplication> ownApp;
-  if (!isMozBrowserElement) {
-    // mAppId corresponds to OwnOrContainingAppId; if isMozBrowserElement is
-    // false then it's ownApp otherwise it's containingApp
-    ownApp = GetAppForId(originAttributes.mAppId);
-    if ((ownApp == nullptr) != (originAttributes.mAppId == NO_APP_ID)) {
-      mInvalidReason = "Got an ownAppId that didn't correspond to an app.";
-      return;
-    }
-  }
-
-  nsCOMPtr<mozIApplication> containingApp = GetAppForId(containingAppId);
-  if ((containingApp == nullptr) != (containingAppId == NO_APP_ID)) {
-    mInvalidReason = "Got a containingAppId that didn't correspond to an app.";
-    return;
-  }
-
   bool rv;
   rv = mTabContext.SetTabContext(isMozBrowserElement,
                                  isPrerendered,
-                                 ownApp,
-                                 containingApp,
                                  showAccelerators,
                                  showFocusRings,
                                  originAttributes,
diff --git a/dom/ipc/TabContext.h b/dom/ipc/TabContext.h
index 48974cad1173..52fb93f67184 100644
--- a/dom/ipc/TabContext.h
+++ b/dom/ipc/TabContext.h
@@ -7,7 +7,6 @@
 #ifndef mozilla_dom_TabContext_h
 #define mozilla_dom_TabContext_h
 
-#include "mozIApplication.h"
 #include "nsCOMPtr.h"
 #include "mozilla/BasePrincipal.h"
 #include "nsPIDOMWindow.h"
@@ -19,9 +18,7 @@ namespace dom {
 class IPCTabContext;
 
 /**
- * TabContext encapsulates information about an iframe that may be a mozbrowser
- * or mozapp.  You can ask whether a TabContext corresponds to a mozbrowser or
- * mozapp, get the app that contains the browser, and so on.
+ * TabContext encapsulates information about an iframe that may be a mozbrowser.
  *
  * TabParent and TabChild both inherit from TabContext, and you can also have
  * standalone TabContext objects.
@@ -38,91 +35,38 @@ public:
   /* (The implicit copy-constructor and operator= are fine.) */
 
   /**
-   * Generates IPCTabContext of type BrowserFrameIPCTabContext or
-   * AppFrameIPCTabContext from this TabContext's information.
+   * Generates IPCTabContext of type BrowserFrameIPCTabContext from this
+   * TabContext's information.
    */
   IPCTabContext AsIPCTabContext() const;
 
   /**
    * Does this TabContext correspond to a mozbrowser?
    *
-   * <iframe mozbrowser mozapp> and <xul:browser> are not considered to be
-   * mozbrowser elements.
-   *
-   * If IsMozBrowserElement() is true, HasOwnApp() and HasAppOwnerApp() are
-   * guaranteed to be false.
-   *
-   * If IsMozBrowserElement() is false, HasBrowserOwnerApp() is guaranteed to be
-   * false.
+   * <iframe mozbrowser> is a mozbrowser element, but <xul:browser> is not.
    */
   bool IsMozBrowserElement() const;
 
   /**
    * Does this TabContext correspond to an isolated mozbrowser?
    *
-   * <iframe mozbrowser mozapp> and <xul:browser> are not considered to be
-   * mozbrowser elements.  <iframe mozbrowser noisolation> does not count as
-   * isolated since isolation is disabled.  Isolation can only be disabled by
-   * chrome pages.
+   * <iframe mozbrowser> is a mozbrowser element, but <xul:browser> is not.
+   * <iframe mozbrowser noisolation> does not count as isolated since isolation
+   * is disabled.  Isolation can only be disabled by chrome pages.
    */
   bool IsIsolatedMozBrowserElement() const;
 
   /**
-   * Does this TabContext correspond to a mozbrowser or mozapp?  This is
-   * equivalent to IsMozBrowserElement() || HasOwnApp().  Returns false for
-   * <xul:browser>, which is neither a mozbrowser nor a mozapp.
+   * Does this TabContext correspond to a mozbrowser?  This is equivalent to
+   * IsMozBrowserElement().  Returns false for <xul:browser>, which isn't a
+   * mozbrowser.
    */
-  bool IsMozBrowserOrApp() const;
-
-  /**
-   * OwnAppId() returns the id of the app which directly corresponds to this
-   * context's frame.  GetOwnApp() returns the corresponding app object, and
-   * HasOwnApp() returns true iff GetOwnApp() would return a non-null value.
-   *
-   * If HasOwnApp() is true, IsMozBrowserElement() is guaranteed to be
-   * false.
-   */
-  uint32_t OwnAppId() const;
-  already_AddRefed<mozIApplication> GetOwnApp() const;
-  bool HasOwnApp() const;
-
-  /**
-   * BrowserOwnerAppId() gets the ID of the app which contains this browser
-   * frame.  If this is not a mozbrowser frame (if !IsMozBrowserElement()), then
-   * BrowserOwnerAppId() is guaranteed to return NO_APP_ID.
-   *
-   * Even if we are a browser frame, BrowserOwnerAppId() may still return
-   * NO_APP_ID, if this browser frame is not contained inside an app.
-   */
-  uint32_t BrowserOwnerAppId() const;
-  already_AddRefed<mozIApplication> GetBrowserOwnerApp() const;
-  bool HasBrowserOwnerApp() const;
-
-  /**
-   * AppOwnerAppId() gets the ID of the app which contains this app frame.  If
-   * this is not an app frame (i.e., if !HasOwnApp()), then AppOwnerAppId() is
-   * guaranteed to return NO_APP_ID.
-   *
-   * Even if we are an app frame, AppOwnerAppId() may still return NO_APP_ID, if
-   * this app frame is not contained inside an app.
-   */
-  uint32_t AppOwnerAppId() const;
-  already_AddRefed<mozIApplication> GetAppOwnerApp() const;
-  bool HasAppOwnerApp() const;
-
-  /**
-   * OwnOrContainingAppId() gets the ID of this frame, if HasOwnApp().  If this
-   * frame does not have its own app, it gets the ID of the app which contains
-   * this frame (i.e., the result of {Browser,App}OwnerAppId(), as applicable).
-   */
-  uint32_t OwnOrContainingAppId() const;
-  already_AddRefed<mozIApplication> GetOwnOrContainingApp() const;
-  bool HasOwnOrContainingApp() const;
+  bool IsMozBrowser() const;
 
   /**
    * OriginAttributesRef() returns the DocShellOriginAttributes of this frame to
    * the caller. This is used to store any attribute associated with the frame's
-   * docshell, such as the AppId.
+   * docshell.
    */
   const DocShellOriginAttributes& OriginAttributesRef() const;
 
@@ -157,17 +101,8 @@ protected:
    */
   void SetPrivateBrowsingAttributes(bool aIsPrivateBrowsing);
 
-  /**
-   * Set the TabContext for this frame. This can either be:
-   *  - an app frame (with the given own app) inside the given owner app. Either
-   *    apps can be null.
-   *  - a browser frame inside the given owner app (which may be null).
-   *  - a non-browser, non-app frame. Both own app and owner app should be null.
-   */
   bool SetTabContext(bool aIsMozBrowserElement,
                      bool aIsPrerendered,
-                     mozIApplication* aOwnApp,
-                     mozIApplication* aAppFrameOwnerApp,
                      UIStateChangeType aShowAccelerators,
                      UIStateChangeType aShowFocusRings,
                      const DocShellOriginAttributes& aOriginAttributes,
@@ -198,29 +133,11 @@ private:
   /**
    * Whether this TabContext corresponds to a mozbrowser.
    *
-   * <iframe mozbrowser mozapp> and <xul:browser> are not considered to be
+   * <iframe mozbrowser> and <xul:browser> are not considered to be
    * mozbrowser elements.
    */
   bool mIsMozBrowserElement;
 
-  /**
-   * This TabContext's own app.  If this is non-null, then this
-   * TabContext corresponds to an app, and mIsMozBrowserElement must be false.
-   */
-  nsCOMPtr<mozIApplication> mOwnApp;
-
-  /**
-   * This TabContext's containing app.  If mIsMozBrowserElement, this
-   * corresponds to the app which contains the browser frame; otherwise, this
-   * corresponds to the app which contains the app frame.
-   */
-  nsCOMPtr<mozIApplication> mContainingApp;
-
-  /*
-   * Cache of mContainingApp->GetLocalId().
-   */
-  uint32_t mContainingAppId;
-
   /**
    * DocShellOriginAttributes of the top level tab docShell
    */
@@ -254,8 +171,6 @@ public:
   bool
   SetTabContext(bool aIsMozBrowserElement,
                 bool aIsPrerendered,
-                mozIApplication* aOwnApp,
-                mozIApplication* aAppFrameOwnerApp,
                 UIStateChangeType aShowAccelerators,
                 UIStateChangeType aShowFocusRings,
                 const DocShellOriginAttributes& aOriginAttributes,
@@ -263,8 +178,6 @@ public:
   {
     return TabContext::SetTabContext(aIsMozBrowserElement,
                                      aIsPrerendered,
-                                     aOwnApp,
-                                     aAppFrameOwnerApp,
                                      aShowAccelerators,
                                      aShowFocusRings,
                                      aOriginAttributes,
@@ -276,10 +189,9 @@ public:
  * MaybeInvalidTabContext is a simple class that lets you transform an
  * IPCTabContext into a TabContext.
  *
- * The issue is that an IPCTabContext is not necessarily valid; for example, it
- * might specify an app-id which doesn't exist.  So to convert an IPCTabContext
- * into a TabContext, you construct a MaybeInvalidTabContext, check whether it's
- * valid, and, if so, read out your TabContext.
+ * The issue is that an IPCTabContext is not necessarily valid.  So to convert
+ * an IPCTabContext into a TabContext, you construct a MaybeInvalidTabContext,
+ * check whether it's valid, and, if so, read out your TabContext.
  *
  * Example usage:
  *
diff --git a/dom/ipc/TabParent.cpp b/dom/ipc/TabParent.cpp
index dd370badcd8b..cbaa4dd5e457 100644
--- a/dom/ipc/TabParent.cpp
+++ b/dom/ipc/TabParent.cpp
@@ -10,7 +10,6 @@
 
 #include "AudioChannelService.h"
 #include "AppProcessChecker.h"
-#include "mozIApplication.h"
 #ifdef ACCESSIBILITY
 #include "mozilla/a11y/DocAccessibleParent.h"
 #include "nsAccessibilityService.h"
@@ -2991,7 +2990,6 @@ public:
   NS_IMETHOD SetUsePrivateBrowsing(bool) NO_IMPL
   NS_IMETHOD SetPrivateBrowsing(bool) NO_IMPL
   NS_IMETHOD GetIsInIsolatedMozBrowserElement(bool*) NO_IMPL
-  NS_IMETHOD GetAppId(uint32_t*) NO_IMPL
   NS_IMETHOD GetOriginAttributes(JS::MutableHandleValue) NO_IMPL
   NS_IMETHOD GetUseRemoteTabs(bool*) NO_IMPL
   NS_IMETHOD SetRemoteTabs(bool) NO_IMPL
diff --git a/dom/ipc/nsIContentChild.cpp b/dom/ipc/nsIContentChild.cpp
index 295a27c3883a..ced10d37f3f9 100644
--- a/dom/ipc/nsIContentChild.cpp
+++ b/dom/ipc/nsIContentChild.cpp
@@ -44,7 +44,6 @@ nsIContentChild::AllocPBrowserChild(const TabId& aTabId,
                                     const IPCTabContext& aContext,
                                     const uint32_t& aChromeFlags,
                                     const ContentParentId& aCpID,
-                                    const bool& aIsForApp,
                                     const bool& aIsForBrowser)
 {
   // We'll happily accept any kind of IPCTabContext here; we don't need to
diff --git a/dom/ipc/nsIContentChild.h b/dom/ipc/nsIContentChild.h
index 864782b1238b..ac931169c954 100644
--- a/dom/ipc/nsIContentChild.h
+++ b/dom/ipc/nsIContentChild.h
@@ -69,7 +69,6 @@ public:
                           const IPCTabContext& aContext,
                           const uint32_t& aChromeFlags,
                           const ContentParentId& aCpID,
-                          const bool& aIsForApp,
                           const bool& aIsForBrowser) = 0;
 
   virtual mozilla::ipc::PFileDescriptorSetChild*
@@ -86,7 +85,6 @@ protected:
                                             const IPCTabContext& aContext,
                                             const uint32_t& aChromeFlags,
                                             const ContentParentId& aCpId,
-                                            const bool& aIsForApp,
                                             const bool& aIsForBrowser);
   virtual bool DeallocPBrowserChild(PBrowserChild*);
 
diff --git a/dom/ipc/nsIContentParent.cpp b/dom/ipc/nsIContentParent.cpp
index 61671ea024c4..bd2fe10207b3 100644
--- a/dom/ipc/nsIContentParent.cpp
+++ b/dom/ipc/nsIContentParent.cpp
@@ -122,11 +122,9 @@ nsIContentParent::AllocPBrowserParent(const TabId& aTabId,
                                       const IPCTabContext& aContext,
                                       const uint32_t& aChromeFlags,
                                       const ContentParentId& aCpId,
-                                      const bool& aIsForApp,
                                       const bool& aIsForBrowser)
 {
   Unused << aCpId;
-  Unused << aIsForApp;
   Unused << aIsForBrowser;
 
   if (!CanOpenBrowser(aContext)) {
diff --git a/dom/ipc/nsIContentParent.h b/dom/ipc/nsIContentParent.h
index 07637e74a322..5cc1d604edec 100644
--- a/dom/ipc/nsIContentParent.h
+++ b/dom/ipc/nsIContentParent.h
@@ -61,7 +61,6 @@ public:
   BlobParent* GetOrCreateActorForBlobImpl(BlobImpl* aImpl);
 
   virtual ContentParentId ChildID() const = 0;
-  virtual bool IsForApp() const = 0;
   virtual bool IsForBrowser() const = 0;
 
   MOZ_MUST_USE virtual PBlobParent*
@@ -74,7 +73,6 @@ public:
                           const IPCTabContext& context,
                           const uint32_t& chromeFlags,
                           const ContentParentId& aCpId,
-                          const bool& aIsForApp,
                           const bool& aIsForBrowser) = 0;
 
   virtual bool IsContentParent() const { return false; }
@@ -100,7 +98,6 @@ protected: // IPDL methods
                                               const IPCTabContext& aContext,
                                               const uint32_t& aChromeFlags,
                                               const ContentParentId& aCpId,
-                                              const bool& aIsForApp,
                                               const bool& aIsForBrowser);
   virtual bool DeallocPBrowserParent(PBrowserParent* frame);
 
diff --git a/dom/media/MediaManager.cpp b/dom/media/MediaManager.cpp
index cd8284ab3b03..f211c42df234 100644
--- a/dom/media/MediaManager.cpp
+++ b/dom/media/MediaManager.cpp
@@ -1906,29 +1906,15 @@ MediaManager::NotifyRecordingStatusChange(nsPIDOMWindowInner* aWindow,
   props->SetPropertyAsBool(NS_LITERAL_STRING("isAudio"), aIsAudio);
   props->SetPropertyAsBool(NS_LITERAL_STRING("isVideo"), aIsVideo);
 
-  bool isApp = false;
-  nsString requestURL;
+  nsCString pageURL;
+  nsCOMPtr<nsIURI> docURI = aWindow->GetDocumentURI();
+  NS_ENSURE_TRUE(docURI, NS_ERROR_FAILURE);
 
-  if (nsCOMPtr<nsIDocShell> docShell = aWindow->GetDocShell()) {
-    isApp = docShell->GetIsApp();
-    if (isApp) {
-      nsresult rv = docShell->GetAppManifestURL(requestURL);
-      NS_ENSURE_SUCCESS(rv, rv);
-    }
-  }
+  nsresult rv = docURI->GetSpec(pageURL);
+  NS_ENSURE_SUCCESS(rv, rv);
 
-  if (!isApp) {
-    nsCString pageURL;
-    nsCOMPtr<nsIURI> docURI = aWindow->GetDocumentURI();
-    NS_ENSURE_TRUE(docURI, NS_ERROR_FAILURE);
+  NS_ConvertUTF8toUTF16 requestURL(pageURL);
 
-    nsresult rv = docURI->GetSpec(pageURL);
-    NS_ENSURE_SUCCESS(rv, rv);
-
-    requestURL = NS_ConvertUTF8toUTF16(pageURL);
-  }
-
-  props->SetPropertyAsBool(NS_LITERAL_STRING("isApp"), isApp);
   props->SetPropertyAsAString(NS_LITERAL_STRING("requestURL"), requestURL);
 
   obs->NotifyObservers(static_cast<nsIPropertyBag2*>(props),
diff --git a/dom/network/TCPServerSocketParent.cpp b/dom/network/TCPServerSocketParent.cpp
index 6b484eaeef65..e0c203160d47 100644
--- a/dom/network/TCPServerSocketParent.cpp
+++ b/dom/network/TCPServerSocketParent.cpp
@@ -65,13 +65,7 @@ TCPServerSocketParent::Init()
 uint32_t
 TCPServerSocketParent::GetAppId()
 {
-  const PContentParent *content = Manager()->Manager();
-  if (PBrowserParent* browser = SingleManagedOrNull(content->ManagedPBrowserParent())) {
-    TabParent *tab = TabParent::GetFrom(browser);
-    return tab->OwnAppId();
-  } else {
-    return nsIScriptSecurityManager::UNKNOWN_APP_ID;
-  }
+  return nsIScriptSecurityManager::UNKNOWN_APP_ID;
 }
 
 bool
diff --git a/dom/network/TCPSocketParent.cpp b/dom/network/TCPSocketParent.cpp
index ecabb00a8b2f..1cacc89be6ac 100644
--- a/dom/network/TCPSocketParent.cpp
+++ b/dom/network/TCPSocketParent.cpp
@@ -73,13 +73,7 @@ TCPSocketParentBase::~TCPSocketParentBase()
 uint32_t
 TCPSocketParent::GetAppId()
 {
-  const PContentParent *content = Manager()->Manager();
-  if (PBrowserParent* browser = SingleManagedOrNull(content->ManagedPBrowserParent())) {
-    TabParent *tab = TabParent::GetFrom(browser);
-    return tab->OwnAppId();
-  } else {
-    return nsIScriptSecurityManager::UNKNOWN_APP_ID;
-  }
+  return nsIScriptSecurityManager::UNKNOWN_APP_ID;
 };
 
 bool
@@ -211,20 +205,15 @@ TCPSocketParent::RecvOpenBind(const nsCString& aRemoteHost,
     }
   }
 
-  // Obtain App ID
-  uint32_t appId = nsIScriptSecurityManager::NO_APP_ID;
   bool     inIsolatedMozBrowser = false;
   const PContentParent *content = Manager()->Manager();
   if (PBrowserParent* browser = SingleManagedOrNull(content->ManagedPBrowserParent())) {
-    // appId's are for B2G only currently, where managees.Count() == 1
-    // This is not guaranteed currently in Desktop, so skip this there.
     TabParent *tab = TabParent::GetFrom(browser);
-    appId = tab->OwnAppId();
     inIsolatedMozBrowser = tab->IsIsolatedMozBrowserElement();
   }
 
   mSocket = new TCPSocket(nullptr, NS_ConvertUTF8toUTF16(aRemoteHost), aRemotePort, aUseSSL, aUseArrayBuffers);
-  mSocket->SetAppIdAndBrowser(appId, inIsolatedMozBrowser);
+  mSocket->SetAppIdAndBrowser(nsIScriptSecurityManager::NO_APP_ID, inIsolatedMozBrowser);
   mSocket->SetSocketBridgeParent(this);
   rv = mSocket->InitWithUnconnectedTransport(socketTransport);
   NS_ENSURE_SUCCESS(rv, IPC_OK());
diff --git a/dom/network/interfaces/nsINetworkStatsServiceProxy.idl b/dom/network/interfaces/nsINetworkStatsServiceProxy.idl
index cd6765c68a4d..123e8122f5a1 100644
--- a/dom/network/interfaces/nsINetworkStatsServiceProxy.idl
+++ b/dom/network/interfaces/nsINetworkStatsServiceProxy.idl
@@ -23,11 +23,11 @@ interface nsINetworkStatsServiceProxy : nsISupports
    * An interface used to record per-app traffic data.
    * @param aAppId app id
    * @param aIsInIsolatedMozBrowser
-   *        true if the frame is an isolated mozbrowser element. <iframe
-   *        mozbrowser mozapp> and <xul:browser> are not considered to be
-   *        mozbrowser elements.  <iframe mozbrowser noisolation> does not count
-   *        as isolated since isolation is disabled.  Isolation can only be
-   *        disabled if the containing document is chrome.
+   *        true if the frame is an isolated mozbrowser element. <xul:browser>
+   *        is not considered to be mozbrowser elements.
+   *        <iframe mozbrowser noisolation> does not count as isolated since
+   *        isolation is disabled.  Isolation can only be disabled if the
+   *        containing document is chrome.
    * @param aNetworkInterface network
    * @param aTimeStamp time stamp
    * @param aRxBytes received data amount
diff --git a/dom/permission/tests/test_embed-apps.html b/dom/permission/tests/test_embed-apps.html
deleted file mode 100644
index 69d4725c7916..000000000000
--- a/dom/permission/tests/test_embed-apps.html
+++ /dev/null
@@ -1,61 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=815105
--->
-<head>
-  <meta charset="utf-8">
-  <title>Test for Bug 815105 </title>
-  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
-</head>
-<body>
-<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=815105">Mozilla Bug 815105 </a>
-<p id="display"></p>
-<div id="content" style="display: none"></div>
-<pre id="test">
-<script type="application/javascript;version=1.8" src="file_framework.js"></script>
-<script type="application/javascript;version=1.8">
-/*
- * embed-apps allows us to create app iframes,
- * creator must also have the browser permission
- */
-function verifier(success, failure) {
-  var iframe = document.createElement('iframe');
-  iframe.setAttribute('mozbrowser', '');
-  iframe.setAttribute('mozapp', 'http://example.org/manifest.webapp');
-  iframe.src = "http://example.org/";
-  iframe.addEventListener('load', function() {
-    var appStatus = SpecialPowers.wrap(iframe)
-                                 .contentDocument.nodePrincipal.appStatus;
-
-    if (appStatus != SpecialPowers.Ci
-                                  .nsIPrincipal.APP_STATUS_NOT_INSTALLED) {
-      success("Got mozapp");
-    } else {
-      failure("Didn't get mozapp") ;
-    }
-  });
-
-  document.getElementById('content').appendChild(iframe);
-}
-
-var gData = [
-  {
-    perm: ["embed-apps", "browser"],
-    /*
-     * Android doesn't have working apps
-     * Mobile is for B2G which has a weird testing setup
-     * the app iframe gets embed in the test-container iframe
-     * which returns APP_STATUS_NOT_INSTALLED
-     */
-    skip: ["Android", "Mobile"],
-    settings: [["dom.mozBrowserFramesEnabled", true]],
-    verifier: verifier.toSource(),
-  }
-]
-</script>
-</pre>
-</body>
-</html>
-
diff --git a/dom/presentation/Presentation.cpp b/dom/presentation/Presentation.cpp
index 07ca12f26d1e..08cb8f2ad7b3 100644
--- a/dom/presentation/Presentation.cpp
+++ b/dom/presentation/Presentation.cpp
@@ -132,7 +132,7 @@ Presentation::HasReceiverSupport() const
   }
 
   if (!Preferences::GetBool("dom.presentation.testing.simulate-receiver") &&
-      !docShell->GetIsInMozBrowserOrApp() &&
+      !docShell->GetIsInMozBrowser() &&
       !docShell->GetIsTopLevelContentDocShell()) {
     return false;
   }
diff --git a/dom/webidl/HTMLIFrameElement.webidl b/dom/webidl/HTMLIFrameElement.webidl
index 0a1b49affec7..6f87c797388e 100644
--- a/dom/webidl/HTMLIFrameElement.webidl
+++ b/dom/webidl/HTMLIFrameElement.webidl
@@ -60,11 +60,5 @@ partial interface HTMLIFrameElement {
            attribute boolean mozbrowser;
 };
 
-partial interface HTMLIFrameElement {
-  // nsIMozBrowserFrame
-  [ChromeOnly]
-  readonly attribute DOMString appManifestURL;
-};
-
 HTMLIFrameElement implements MozFrameLoaderOwner;
 HTMLIFrameElement implements BrowserElement;
diff --git a/dom/webidl/MozNetworkStats.webidl b/dom/webidl/MozNetworkStats.webidl
index dc8635b87dea..3c2b66e0cdc8 100644
--- a/dom/webidl/MozNetworkStats.webidl
+++ b/dom/webidl/MozNetworkStats.webidl
@@ -20,7 +20,7 @@ dictionary NetworkStatsGetOptions
    * If it is set as true, only the browsing traffic, which is generated from
    * the mozbrowser iframe element within an app, is returned in result.
    * If it is set as false or not set, the total traffic, which is generated
-   * from both the mozapp and mozbrowser iframe elements, is returned.
+   * from mozbrowser iframe elements, is returned.
    */
   boolean browsingTrafficOnly = false;
 };
diff --git a/dom/xul/nsXULElement.cpp b/dom/xul/nsXULElement.cpp
index 14fa898ab5ef..b579aa93179c 100644
--- a/dom/xul/nsXULElement.cpp
+++ b/dom/xul/nsXULElement.cpp
@@ -1632,17 +1632,6 @@ nsXULElement::GetFrameLoader()
     return already_AddRefed<nsFrameLoader>(static_cast<nsFrameLoader*>(loader.forget().take()));
 }
 
-nsresult
-nsXULElement::GetParentApplication(mozIApplication** aApplication)
-{
-    if (!aApplication) {
-        return NS_ERROR_FAILURE;
-    }
-
-    *aApplication = nullptr;
-    return NS_OK;
-}
-
 void
 nsXULElement::PresetOpenerWindow(mozIDOMWindowProxy* aWindow, ErrorResult& aRv)
 {
diff --git a/dom/xul/nsXULElement.h b/dom/xul/nsXULElement.h
index 164afacd32ee..16ce5ded2f95 100644
--- a/dom/xul/nsXULElement.h
+++ b/dom/xul/nsXULElement.h
@@ -411,7 +411,6 @@ public:
     virtual mozilla::EventStates IntrinsicState() const override;
 
     nsresult GetFrameLoaderXPCOM(nsIFrameLoader** aFrameLoader);
-    nsresult GetParentApplication(mozIApplication** aApplication);
     void PresetOpenerWindow(mozIDOMWindowProxy* aWindow, ErrorResult& aRv);
     nsresult SetIsPrerendered();
 
diff --git a/embedding/components/windowwatcher/nsWindowWatcher.cpp b/embedding/components/windowwatcher/nsWindowWatcher.cpp
index f88bf47c3d3a..7e00a92937f2 100644
--- a/embedding/components/windowwatcher/nsWindowWatcher.cpp
+++ b/embedding/components/windowwatcher/nsWindowWatcher.cpp
@@ -1987,7 +1987,7 @@ nsWindowWatcher::CalculateChromeFlagsForParent(mozIDOMWindowProxy* aParent,
   // Disable CHROME_OPENAS_DIALOG if the window is inside <iframe mozbrowser>.
   // It's up to the embedder to interpret what dialog=1 means.
   nsCOMPtr<nsIDocShell> docshell = do_GetInterface(aParent);
-  if (docshell && docshell->GetIsInMozBrowserOrApp()) {
+  if (docshell && docshell->GetIsInMozBrowser()) {
     chromeFlags &= ~nsIWebBrowserChrome::CHROME_OPENAS_DIALOG;
   }
 
diff --git a/extensions/cookie/nsPermissionManager.cpp b/extensions/cookie/nsPermissionManager.cpp
index d3696dd94877..fc07c875ce0a 100644
--- a/extensions/cookie/nsPermissionManager.cpp
+++ b/extensions/cookie/nsPermissionManager.cpp
@@ -30,7 +30,6 @@
 #include "nsContentUtils.h"
 #include "nsIScriptSecurityManager.h"
 #include "nsIAppsService.h"
-#include "mozIApplication.h"
 #include "nsIEffectiveTLDService.h"
 #include "nsPIDOMWindow.h"
 #include "nsIDocument.h"
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 3ac1caa0bf14..6948ab87ea46 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -6996,20 +6996,6 @@ CheckPermissionForBeforeAfterKeyboardEvent(Element* aElement)
     if (permission == nsIPermissionManager::ALLOW_ACTION) {
       return true;
     }
-
-    // Check "embed-apps" permission for later use.
-    permission = nsIPermissionManager::DENY_ACTION;
-    permMgr->TestPermissionFromPrincipal(principal, "embed-apps", &permission);
-  }
-
-  // An element can handle before events and after events if the following
-  // conditions are met:
-  // 1) <iframe mozbrowser mozapp>
-  // 2) it has "embed-apps" permission.
-  nsCOMPtr<nsIMozBrowserFrame> browserFrame(do_QueryInterface(aElement));
-  if ((permission == nsIPermissionManager::ALLOW_ACTION) &&
-      browserFrame && browserFrame->GetReallyIsApp()) {
-    return true;
   }
 
   return false;
diff --git a/layout/generic/nsViewportFrame.cpp b/layout/generic/nsViewportFrame.cpp
index 39491a0edc41..3169759e0451 100644
--- a/layout/generic/nsViewportFrame.cpp
+++ b/layout/generic/nsViewportFrame.cpp
@@ -86,7 +86,7 @@ ShouldInTopLayerForFullscreen(Element* aElement)
     return false;
   }
   nsCOMPtr<nsIMozBrowserFrame> browserFrame = do_QueryInterface(aElement);
-  if (browserFrame && browserFrame->GetReallyIsBrowserOrApp()) {
+  if (browserFrame && browserFrame->GetReallyIsBrowser()) {
     return false;
   }
   return true;
diff --git a/layout/style/nsCSSRuleProcessor.cpp b/layout/style/nsCSSRuleProcessor.cpp
index 07a4ef57b32d..5e3fb5ee9ebd 100644
--- a/layout/style/nsCSSRuleProcessor.cpp
+++ b/layout/style/nsCSSRuleProcessor.cpp
@@ -2075,7 +2075,7 @@ static bool SelectorMatches(Element* aElement,
           nsCOMPtr<nsIMozBrowserFrame>
             browserFrame = do_QueryInterface(aElement);
           if (!browserFrame ||
-              !browserFrame->GetReallyIsBrowserOrApp()) {
+              !browserFrame->GetReallyIsBrowser()) {
             return false;
           }
         }
diff --git a/layout/tools/reftest/reftest.jsm b/layout/tools/reftest/reftest.jsm
index 11d6029e4e2c..d3f0ef5e1e6b 100644
--- a/layout/tools/reftest/reftest.jsm
+++ b/layout/tools/reftest/reftest.jsm
@@ -309,7 +309,6 @@ this.OnRefTestLoad = function OnRefTestLoad(win)
     if (gBrowserIsIframe) {
       gBrowser = gContainingWindow.document.createElementNS(XHTML_NS, "iframe");
       gBrowser.setAttribute("mozbrowser", "");
-      gBrowser.setAttribute("mozapp", prefs.getCharPref("b2g.system_manifest_url"));
     } else {
       gBrowser = gContainingWindow.document.createElementNS(XUL_NS, "xul:browser");
     }
diff --git a/mobile/android/chrome/content/browser.js b/mobile/android/chrome/content/browser.js
index ad5543c7bc48..eb0dc1b785ab 100644
--- a/mobile/android/chrome/content/browser.js
+++ b/mobile/android/chrome/content/browser.js
@@ -3416,15 +3416,6 @@ Tab.prototype = {
     BrowserApp.deck.selectedPanel = selectedPanel;
 
     let attrs = {};
-    if (BrowserApp.manifestUrl) {
-      let appsService = Cc["@mozilla.org/AppsService;1"].getService(Ci.nsIAppsService);
-      let manifest = appsService.getAppByManifestURL(BrowserApp.manifestUrl);
-      if (manifest) {
-        let app = manifest.QueryInterface(Ci.mozIApplication);
-        this.browser.docShell.frameType = Ci.nsIDocShell.FRAME_TYPE_APP;
-        attrs['appId'] = app.localId;
-      }
-    }
 
     // Must be called after appendChild so the docShell has been created.
     this.setActive(false);
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index f7ceac780573..800f81d11d1c 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -963,8 +963,6 @@ pref("devtools.debugger.force-local", true);
 pref("devtools.debugger.prompt-connection", true);
 // Block tools from seeing / interacting with certified apps
 pref("devtools.debugger.forbid-certified-apps", true);
-// List of permissions that a sideloaded app can't ask for
-pref("devtools.apps.forbidden-permissions", "embed-apps");
 
 // DevTools default color unit
 pref("devtools.defaultColorUnit", "authored");
diff --git a/netwerk/base/nsNetUtil.cpp b/netwerk/base/nsNetUtil.cpp
index 8ff3e788f337..6d18c844224b 100644
--- a/netwerk/base/nsNetUtil.cpp
+++ b/netwerk/base/nsNetUtil.cpp
@@ -568,15 +568,12 @@ NS_LoadGroupMatchesPrincipal(nsILoadGroup *aLoadGroup,
                                   getter_AddRefs(loadContext));
     NS_ENSURE_TRUE(loadContext, false);
 
-    // Verify load context appId and browser flag match the principal
-    uint32_t contextAppId;
+    // Verify load context browser flag match the principal
     bool contextInIsolatedBrowser;
-    nsresult rv = loadContext->GetAppId(&contextAppId);
-    NS_ENSURE_SUCCESS(rv, false);
-    rv = loadContext->GetIsInIsolatedMozBrowserElement(&contextInIsolatedBrowser);
+    nsresult rv = loadContext->GetIsInIsolatedMozBrowserElement(&contextInIsolatedBrowser);
     NS_ENSURE_SUCCESS(rv, false);
 
-    return contextAppId == aPrincipal->GetAppId() &&
+    return nsIScriptSecurityManager::NO_APP_ID == aPrincipal->GetAppId() &&
            contextInIsolatedBrowser == aPrincipal->GetIsInIsolatedMozBrowserElement();
 }
 
@@ -2394,14 +2391,8 @@ NS_CompareLoadInfoAndLoadContext(nsIChannel *aChannel)
     return NS_OK;
   }
 
-  uint32_t loadContextAppId = 0;
-  nsresult rv = loadContext->GetAppId(&loadContextAppId);
-  if (NS_FAILED(rv)) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
   bool loadContextIsInBE = false;
-  rv = loadContext->GetIsInIsolatedMozBrowserElement(&loadContextIsInBE);
+  nsresult rv = loadContext->GetIsInIsolatedMozBrowserElement(&loadContextIsInBE);
   if (NS_FAILED(rv)) {
     return NS_ERROR_UNEXPECTED;
   }
@@ -2411,17 +2402,13 @@ NS_CompareLoadInfoAndLoadContext(nsIChannel *aChannel)
   loadContext->GetOriginAttributes(originAttrsLoadContext);
 
   LOG(("NS_CompareLoadInfoAndLoadContext - loadInfo: %d, %d, %d, %d; "
-       "loadContext: %d %d, %d, %d. [channel=%p]",
+       "loadContext: %d %d, %d. [channel=%p]",
        originAttrsLoadInfo.mAppId, originAttrsLoadInfo.mInIsolatedMozBrowser,
        originAttrsLoadInfo.mUserContextId, originAttrsLoadInfo.mPrivateBrowsingId,
-       loadContextAppId, loadContextIsInBE,
+       loadContextIsInBE,
        originAttrsLoadContext.mUserContextId, originAttrsLoadContext.mPrivateBrowsingId,
        aChannel));
 
-  MOZ_ASSERT(originAttrsLoadInfo.mAppId == loadContextAppId,
-             "AppId in the loadContext and in the loadInfo are not the "
-             "same!");
-
   MOZ_ASSERT(originAttrsLoadInfo.mInIsolatedMozBrowser ==
              loadContextIsInBE,
              "The value of InIsolatedMozBrowser in the loadContext and in "
diff --git a/netwerk/cookie/nsCookieService.cpp b/netwerk/cookie/nsCookieService.cpp
index 790df9db7d5c..fb6770ace258 100644
--- a/netwerk/cookie/nsCookieService.cpp
+++ b/netwerk/cookie/nsCookieService.cpp
@@ -51,7 +51,6 @@
 #include "mozilla/FileUtils.h"
 #include "mozilla/Telemetry.h"
 #include "nsIAppsService.h"
-#include "mozIApplication.h"
 #include "mozIApplicationClearPrivateDataParams.h"
 #include "nsIConsoleService.h"
 #include "nsVariant.h"
diff --git a/netwerk/ipc/NeckoParent.cpp b/netwerk/ipc/NeckoParent.cpp
index 06b15b91ff54..a549d72c068c 100644
--- a/netwerk/ipc/NeckoParent.cpp
+++ b/netwerk/ipc/NeckoParent.cpp
@@ -177,20 +177,8 @@ NeckoParent::GetValidatedAppInfo(const SerializedLoadContext& aSerialized,
   nsAutoCString debugString;
   for (uint32_t i = 0; i < contextArray.Length(); i++) {
     TabContext tabContext = contextArray[i];
-    uint32_t appId = tabContext.OwnOrContainingAppId();
     bool inBrowserElement = aSerialized.mOriginAttributes.mInIsolatedMozBrowser;
 
-    if (appId == NECKO_UNKNOWN_APP_ID) {
-      debugString.Append("u,");
-      continue;
-    }
-    // We may get appID=NO_APP if child frame is neither a browser nor an app
-    if (appId == NECKO_NO_APP_ID && tabContext.HasOwnApp()) {
-      // NECKO_NO_APP_ID but also is an app?  Weird, skip.
-      debugString.Append("h,");
-      continue;
-    }
-
     if (aSerialized.mOriginAttributes.mUserContextId != tabContext.OriginAttributesRef().mUserContextId) {
       debugString.Append("(");
       debugString.AppendInt(aSerialized.mOriginAttributes.mUserContextId);
@@ -200,7 +188,7 @@ NeckoParent::GetValidatedAppInfo(const SerializedLoadContext& aSerialized,
       continue;
     }
     aAttrs = DocShellOriginAttributes();
-    aAttrs.mAppId = appId;
+    aAttrs.mAppId = nsIScriptSecurityManager::NO_APP_ID;
     aAttrs.mInIsolatedMozBrowser = inBrowserElement;
     aAttrs.mUserContextId = aSerialized.mOriginAttributes.mUserContextId;
     aAttrs.mPrivateBrowsingId = aSerialized.mOriginAttributes.mPrivateBrowsingId;
diff --git a/netwerk/test/unit_ipc/child_app_offline_notifications.js b/netwerk/test/unit_ipc/child_app_offline_notifications.js
deleted file mode 100644
index 870c22b39740..000000000000
--- a/netwerk/test/unit_ipc/child_app_offline_notifications.js
+++ /dev/null
@@ -1,43 +0,0 @@
-Cu.import("resource://gre/modules/Services.jsm");
-Cu.import("resource://gre/modules/XPCOMUtils.jsm");
-
-function is_app_offline(appId) {
-  let ioservice = Cc['@mozilla.org/network/io-service;1'].
-    getService(Ci.nsIIOService);
-  return ioservice.isAppOffline(appId);
-}
-
-var events_observed_no = 0;
-
-// Holds the last observed app-offline event
-var info = null;
-function observer(aSubject, aTopic, aData) {
-  events_observed_no++;
-  info = aSubject.QueryInterface(Ci.nsIAppOfflineInfo);
-  dump("ChildObserver - subject: {" + aSubject.appId + ", " + aSubject.mode + "} ");
-}
-
-// Add observer for the app-offline notification
-function run_test() {
-  Services.obs.addObserver(observer, "network:app-offline-status-changed", false);
-}
-
-// Chech that the app has the proper offline status
-function check_status(appId, status)
-{
-  do_check_eq(is_app_offline(appId), status == Ci.nsIAppOfflineInfo.OFFLINE);
-}
-
-// Check that the app has the proper offline status
-// and that the correct notification has been received
-function check_notification_and_status(appId, status) {
-  do_check_eq(info.appId, appId);
-  do_check_eq(info.mode, status);
-  do_check_eq(is_app_offline(appId), status == Ci.nsIAppOfflineInfo.OFFLINE);
-}
-
-// Remove the observer from the child process
-function finished() {
-  Services.obs.removeObserver(observer, "network:app-offline-status-changed");
-  do_check_eq(events_observed_no, 2);
-}
diff --git a/testing/mochitest/manifest.webapp b/testing/mochitest/manifest.webapp
index a3c2e2592b02..a1c03e257b91 100644
--- a/testing/mochitest/manifest.webapp
+++ b/testing/mochitest/manifest.webapp
@@ -24,7 +24,6 @@
     "desktop-notification":{},
     "idle":{},
     "network-events":{},
-    "embed-apps":{},
     "audio-channel-content":{},
     "audio-channel-alarm":{},
     "before-after-keyboard-event":{}
diff --git a/uriloader/prefetch/OfflineCacheUpdateParent.cpp b/uriloader/prefetch/OfflineCacheUpdateParent.cpp
index 0381ec3f6233..55a16b19d9da 100644
--- a/uriloader/prefetch/OfflineCacheUpdateParent.cpp
+++ b/uriloader/prefetch/OfflineCacheUpdateParent.cpp
@@ -263,13 +263,6 @@ OfflineCacheUpdateParent::GetIsInIsolatedMozBrowserElement(bool *aIsInIsolatedMo
     return mLoadingPrincipal->GetIsInIsolatedMozBrowserElement(aIsInIsolatedMozBrowserElement);
 }
 
-NS_IMETHODIMP
-OfflineCacheUpdateParent::GetAppId(uint32_t *aAppId)
-{
-    NS_ENSURE_TRUE(mLoadingPrincipal, NS_ERROR_UNEXPECTED);
-    return mLoadingPrincipal->GetAppId(aAppId);
-}
-
 NS_IMETHODIMP
 OfflineCacheUpdateParent::GetOriginAttributes(JS::MutableHandleValue aAttrs)
 {
diff --git a/widget/gonk/GonkPermission.cpp b/widget/gonk/GonkPermission.cpp
index 8ebc43de843f..5bdd07738e99 100644
--- a/widget/gonk/GonkPermission.cpp
+++ b/widget/gonk/GonkPermission.cpp
@@ -28,8 +28,6 @@
 #include "mozilla/dom/ContentParent.h"
 #include "mozilla/dom/TabParent.h"
 #include "mozilla/SyncRunnable.h"
-#include "nsIAppsService.h"
-#include "mozIApplication.h"
 #include "nsThreadUtils.h"
 
 #undef LOG
@@ -40,81 +38,6 @@
 using namespace android;
 using namespace mozilla;
 
-// Checking permissions needs to happen on the main thread, but the
-// binder callback is called on a special binder thread, so we use
-// this runnable for that.
-class GonkPermissionChecker : public Runnable {
-  int32_t mPid;
-  bool mCanUseCamera;
-
-  explicit GonkPermissionChecker(int32_t pid)
-    : mPid(pid)
-    , mCanUseCamera(false)
-  {
-  }
-
-public:
-  static already_AddRefed<GonkPermissionChecker> Inspect(int32_t pid)
-  {
-    RefPtr<GonkPermissionChecker> that = new GonkPermissionChecker(pid);
-    nsCOMPtr<nsIThread> mainThread = do_GetMainThread();
-    MOZ_ASSERT(mainThread);
-    SyncRunnable::DispatchToThread(mainThread, that);
-    return that.forget();
-  }
-
-  bool CanUseCamera()
-  {
-    return mCanUseCamera;
-  }
-
-  NS_IMETHOD Run();
-};
-
-NS_IMETHODIMP
-GonkPermissionChecker::Run()
-{
-  MOZ_ASSERT(NS_IsMainThread());
-
-  // Find our ContentParent.
-  dom::ContentParent *contentParent = nullptr;
-  {
-    nsTArray<dom::ContentParent*> parents;
-    dom::ContentParent::GetAll(parents);
-    for (uint32_t i = 0; i < parents.Length(); ++i) {
-      if (parents[i]->Pid() == mPid) {
-	contentParent = parents[i];
-	break;
-      }
-    }
-  }
-  if (!contentParent) {
-    ALOGE("pid=%d denied: can't find ContentParent", mPid);
-    return NS_OK;
-  }
-
-  // Now iterate its apps...
-  const ManagedContainer<dom::PBrowserParent>& browsers =
-    contentParent->ManagedPBrowserParent();
-  for (auto iter = browsers.ConstIter(); !iter.Done(); iter.Next()) {
-    dom::TabParent *tabParent =
-      static_cast<dom::TabParent*>(iter.Get()->GetKey());
-    nsCOMPtr<mozIApplication> mozApp = tabParent->GetOwnOrContainingApp();
-    if (!mozApp) {
-      continue;
-    }
-
-    // ...and check if any of them has camera access.
-    bool appCanUseCamera;
-    nsresult rv = mozApp->HasPermission("camera", &appCanUseCamera);
-    if (NS_SUCCEEDED(rv) && appCanUseCamera) {
-      mCanUseCamera = true;
-      return NS_OK;
-    }
-  }
-  return NS_OK;
-}
-
 bool
 GonkPermissionService::checkPermission(const String16& permission, int32_t pid,
                                      int32_t uid)
@@ -153,19 +76,9 @@ GonkPermissionService::checkPermission(const String16& permission, int32_t pid,
   PermissionGrant permGrant(perm8.string(), pid);
   if (nsTArray<PermissionGrant>::NoIndex != mGrantArray.IndexOf(permGrant)) {
     mGrantArray.RemoveElement(permGrant);
-    return true;
   }
 
-  // Camera/audio record permissions are allowed for apps with the
-  // "camera" permission.
-  RefPtr<GonkPermissionChecker> checker =
-    GonkPermissionChecker::Inspect(pid);
-  bool canUseCamera = checker->CanUseCamera();
-  if (!canUseCamera) {
-    ALOGE("%s for pid=%d,uid=%d denied: not granted by user or app manifest",
-      String8(permission).string(), pid, uid);
-  }
-  return canUseCamera;
+  return true;
 }
 
 static GonkPermissionService* gGonkPermissionService = NULL;
diff --git a/xpfe/appshell/nsContentTreeOwner.cpp b/xpfe/appshell/nsContentTreeOwner.cpp
index b39b7610fb6a..815036d0c920 100644
--- a/xpfe/appshell/nsContentTreeOwner.cpp
+++ b/xpfe/appshell/nsContentTreeOwner.cpp
@@ -818,7 +818,7 @@ nsContentTreeOwner::ProvideWindow(mozIDOMWindowProxy* aParent,
   // open a modal-type window, we're going to create a new <iframe mozbrowser>
   // and return its window here.
   nsCOMPtr<nsIDocShell> docshell = do_GetInterface(aParent);
-  if (docshell && docshell->GetIsInMozBrowserOrApp() &&
+  if (docshell && docshell->GetIsInMozBrowser() &&
       !(aChromeFlags & (nsIWebBrowserChrome::CHROME_MODAL |
                         nsIWebBrowserChrome::CHROME_OPENAS_DIALOG |
                         nsIWebBrowserChrome::CHROME_OPENAS_CHROME))) {